https://shio-chan-dev.github.io/jeanblog/Recent content on Jeanphilo BlogHugo -- 0.159.2en-usFri, 03 Apr 2026 17:54:22 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/backtracking/46-permutations/Fri, 03 Apr 2026 17:54:22 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/backtracking/46-permutations/A practical guide to LeetCode 46 covering used[] state tracking, leaf-only collection, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/backtracking/78-subsets/Thu, 02 Apr 2026 13:48:57 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/backtracking/78-subsets/A practical guide to LeetCode 78 covering subset backtracking, the startIndex invariant, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/133-clone-graph/Thu, 19 Mar 2026 13:18:26 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/133-clone-graph/Clone a connected undirected graph by mapping original nodes to cloned nodes, with DFS and BFS variants, cycle handling, correctness reasoning, and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/2089-find-target-indices-after-sorting-array/Wed, 18 Mar 2026 13:49:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/2089-find-target-indices-after-sorting-array/Sort the array, locate the target block with lower and upper bounds, and return every target index, with tradeoff analysis, engineering mappings, and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/2529-maximum-count-of-positive-integer-and-negative-integer/Wed, 18 Mar 2026 13:49:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/2529-maximum-count-of-positive-integer-and-negative-integer/Count negatives and positives in a sorted array by locating the boundaries around zero with lower-bound and upper-bound binary search, with engineering mappings and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/34-find-first-and-last-position-of-element-in-sorted-array/Wed, 18 Mar 2026 13:49:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/34-find-first-and-last-position-of-element-in-sorted-array/Find the start and end positions of a target in a sorted array by combining lower-bound and upper-bound binary search, with boundary reasoning, engineering mappings, and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/35-search-insert-position/Wed, 18 Mar 2026 13:49:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/35-search-insert-position/Find the insertion index of a target in a sorted array with lower-bound binary search in O(log n), with boundary reasoning, engineering mappings, and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/744-find-smallest-letter-greater-than-target/Wed, 18 Mar 2026 13:49:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/binary-search/744-find-smallest-letter-greater-than-target/Find the smallest character strictly greater than a target in a sorted circular array by using upper-bound binary search and wrap-around logic, with pitfalls, engineering mappings, and runnable implementations in six languages.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/102-binary-tree-level-order-traversal/Mon, 16 Mar 2026 13:00:56 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/102-binary-tree-level-order-traversal/A practical guide to LeetCode 102 covering level-by-level BFS, level-size boundaries, DFS depth buckets, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/101-symmetric-tree/Mon, 16 Mar 2026 13:00:55 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/101-symmetric-tree/A practical guide to LeetCode 101 covering mirror recursion, pairwise BFS checks, symmetry contracts, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/100-same-tree/Mon, 16 Mar 2026 13:00:54 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/100-same-tree/A practical guide to LeetCode 100 covering synchronous recursion, pairwise BFS validation, structural equivalence, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/226-invert-binary-tree/Fri, 06 Mar 2026 17:58:23 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/226-invert-binary-tree/A practical guide to LeetCode 226 covering tree mirroring, recursive left-right swaps, BFS traversal, and engineering mappings.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/104-maximum-depth-of-binary-tree/Fri, 06 Mar 2026 17:58:22 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/104-maximum-depth-of-binary-tree/A practical guide to LeetCode 104 covering the depth definition, recursive DFS, level-order BFS, engineering mappings, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/94-binary-tree-inorder-traversal/Fri, 06 Mar 2026 17:58:21 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/binary-tree/94-binary-tree-inorder-traversal/A practical guide to LeetCode 94 covering left-root-right traversal, recursion, explicit stacks, engineering mappings, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/146-lru-cache/Thu, 12 Feb 2026 13:51:08 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/146-lru-cache/Implement LRUCache with O(1) average get/put by combining a hash map for lookup and a doubly linked list for recency order. Includes ACERS reasoning, engineering mapping, and runnable multi-language code.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/19-remove-nth-node-from-end-of-list/Thu, 12 Feb 2026 13:50:28 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/19-remove-nth-node-from-end-of-list/From naive two-pass traversal to one-pass fast/slow pointers, this ACERS guide explains Remove Nth Node From End of List with correctness intuition, edge cases, engineering mappings, and runnable multi-language code.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/linked-list/138-copy-list-with-random-pointer/Wed, 11 Feb 2026 07:59:32 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/linked-list/138-copy-list-with-random-pointer/The core of copying a random-pointer list is mapping original node identity to copied node identity, then rebuilding next/random pointers. This article uses the ACERS structure to cover intuition, engineering analogies, pitfalls, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2-add-two-numbers/Wed, 11 Feb 2026 07:54:26 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2-add-two-numbers/Add two non-negative integers represented by reverse-order linked lists. This ACERS-style guide explains digit-by-digit carry propagation with engineering mappings and runnable multi-language code.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/148-sort-list/Tue, 10 Feb 2026 17:07:38 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/148-sort-list/Sort a singly linked list in O(n log n) time using split + recursive merge sort. This guide explains derivation, invariants, engineering mappings, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/23-merge-k-sorted-lists/Tue, 10 Feb 2026 17:05:53 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/23-merge-k-sorted-lists/Upgrade from LeetCode 21 to k-way merge: derive why sequential merge degrades, then use divide-and-conquer to reach O(N log k), with heap comparison and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/142-linked-list-cycle-ii/Tue, 10 Feb 2026 10:47:56 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/142-linked-list-cycle-ii/Return the first node where a singly linked list enters a cycle without modifying the list: use Floyd fast/slow pointers to detect a meeting point, then reset one pointer to head and move both one step to localize the entry in O(n) time and O(1) space.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/21-merge-two-sorted-lists/Tue, 10 Feb 2026 10:47:02 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/21-merge-two-sorted-lists/Merge two sorted linked lists in O(m+n) with sentinel node and two pointers, with iterative and recursive comparison, engineering mapping, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/41-first-missing-positive/Tue, 10 Feb 2026 10:25:53 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/41-first-missing-positive/Find the first missing positive in O(n) time and O(1) extra space using in-place index placement (value x should be placed at index x-1), with engineering mapping, pitfalls, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/25-reverse-nodes-in-k-group/Tue, 10 Feb 2026 10:25:53 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/25-reverse-nodes-in-k-group/Reverse a linked list in groups of k nodes in-place, leaving the last group unchanged if its size is smaller than k. This guide presents a dummy-node + kth-scan + in-place reversal template in O(n) time and O(1) extra space.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/143-reorder-list/Tue, 10 Feb 2026 09:57:31 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/143-reorder-list/Reorder a linked list to L0-&gt;Ln-&gt;L1-&gt;Ln-1... in O(n) time and O(1) extra space using split, reverse, and alternating merge, with derivation, pitfalls, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/92-reverse-linked-list-ii/Tue, 10 Feb 2026 09:56:14 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/92-reverse-linked-list-ii/Reverse only the interval [left, right] in a singly linked list using a dummy node and in-place head insertion. O(n) time, O(1) extra space, with derivation, pitfalls, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/141-linked-list-cycle/Tue, 10 Feb 2026 08:55:58 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/141-linked-list-cycle/Detect whether a singly linked list has a cycle using Floyd fast/slow pointers in O(n) time and O(1) extra space, with proof intuition, pitfalls, engineering mapping, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/234-palindrome-linked-list/Mon, 09 Feb 2026 17:38:32 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/234-palindrome-linked-list/Check whether a singly linked list is a palindrome in O(n) time and O(1) extra space: find middle with fast/slow pointers, reverse second half, compare, then restore list structure.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/206-reverse-linked-list/Mon, 09 Feb 2026 17:27:59 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/206-reverse-linked-list/Reverse a singly linked list in O(n) time and O(1) extra space with the three-pointer iterative template, with recursive comparison, engineering mapping, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/560-subarray-sum-equals-k/Mon, 09 Feb 2026 13:19:45 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/560-subarray-sum-equals-k/Count subarrays whose sum equals k in O(n) using prefix sum and frequency hash map, with engineering scenarios, pitfalls, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/00-graph-algorithms-learning-path/Mon, 09 Feb 2026 10:14:45 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/00-graph-algorithms-learning-path/A graph algorithms topic guide and recommended reading order covering BFS/DFS, reachability, shortest paths, CC/SCC, centrality, PageRank, community detection, subgraph matching, dynamic graphs, graph partitioning, and graph computation models.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/110-graph-computation-models-pregel-gas-parallel-bfs/Mon, 09 Feb 2026 10:05:33 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/110-graph-computation-models-pregel-gas-parallel-bfs/An engineering implementation framework centered on graph computation models: core abstractions, synchronization semantics, performance boundaries of Pregel and GAS, plus implementation and selection guidance for PageRank/CC/parallel BFS.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/100-graph-partitioning-edge-cut-vertex-cut-metis/Mon, 09 Feb 2026 10:04:05 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/100-graph-partitioning-edge-cut-vertex-cut-metis/A practical graph partitioning guide for production graph databases, covering Edge-cut vs Vertex-cut, the core METIS workflow, runnable examples, and an engineering tuning checklist.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/90-dynamic-graph-incremental-computation/Mon, 09 Feb 2026 10:00:28 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/90-dynamic-graph-incremental-computation/For real-world graph systems, this article systematically explains dynamic graph incremental algorithms: incremental shortest path, incremental PageRank, and connectivity maintenance. It focuses on three core engineering techniques: local recomputation, lazy updates, and approximate results.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/80-community-detection-louvain-label-propagation/Mon, 09 Feb 2026 09:59:58 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/80-community-detection-louvain-label-propagation/Centered on three core community-detection use cases (group identification, graph partitioning, and cold-start analysis), this article explains Louvain and Label Propagation with principles, complexity, engineering trade-offs, and runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/70-subgraph-matching-vf2-ullmann-and-pruning/Mon, 09 Feb 2026 09:59:16 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/70-subgraph-matching-vf2-ullmann-and-pruning/A systematic guide to Subgraph Isomorphism (NP-hard) and the core ideas of VF2/Ullmann, with emphasis on engineering reality: constrained pattern queries and candidate pruning usually matter more than the algorithm name itself.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/50-graph-centrality-degree-betweenness-closeness/Mon, 09 Feb 2026 09:56:11 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/50-graph-centrality-degree-betweenness-closeness/A systematic guide to the three core graph centrality metrics: Degree, Betweenness, and Closeness. The key engineering takeaway: most production systems prioritize Degree and approximate Betweenness, with clear complexity and rollout tradeoffs.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/60-pagerank-and-personalized-pagerank/Mon, 09 Feb 2026 09:54:25 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/60-pagerank-and-personalized-pagerank/A systematic explanation of PageRank and Personalized PageRank, from iterative computation and sparse-matrix implementation to incremental update strategies, covering core graph-database scenarios such as recommendation and influence analysis.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/30-k-hop-reachability-and-reach-index/Mon, 09 Feb 2026 09:52:17 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/30-k-hop-reachability-and-reach-index/A systematic engineering guide to k-hop and reachability queries: BFS+hop limits, why full transitive closure is usually not maintained, and practical bitmap/2-hop reach-index strategies with runnable multi-language code.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/40-connected-components-and-scc-tarjan-kosaraju/Mon, 09 Feb 2026 09:50:22 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/40-connected-components-and-scc-tarjan-kosaraju/A systematic guide to undirected Connected Components and directed SCCs, with emphasis on Tarjan (common in production) and Kosaraju, mapped to graph-database scenarios such as community pre-grouping, subgraph splitting, and partition hints.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/20-shortest-path-bfs-dijkstra-astar-acers/Mon, 09 Feb 2026 09:48:00 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/20-shortest-path-bfs-dijkstra-astar-acers/A full engineering walkthrough of the shortest-path core trio: BFS for unweighted graphs, Dijkstra for non-negative weights, and heuristic A*. Includes multi-source BFS, bidirectional search, path pruning, and runnable multi-language templates.https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/10-bfs-dfs-k-hop-subgraph-path-existence/Mon, 09 Feb 2026 09:44:11 +0800https://shio-chan-dev.github.io/jeanblog/dev/algorithm/graph/10-bfs-dfs-k-hop-subgraph-path-existence/Centered on three high-frequency graph tasks (k-hop query, subgraph extraction, and path existence), this article explains practical BFS/DFS iteration templates, early-stop pruning, and visited bitmap/bloom choices with runnable multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/160-intersection-of-two-linked-lists/Mon, 09 Feb 2026 09:26:37 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/160-intersection-of-two-linked-lists/Find the intersection node of two singly linked lists without modifying structure: two pointers switching heads synchronize in O(m+n) time and O(1) extra space, with derivation, engineering mapping, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/437-path-sum-iii/Wed, 04 Feb 2026 16:02:26 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/437-path-sum-iii/Count downward paths in a binary tree whose sum equals targetSum in O(n) using prefix sums and a frequency hash map, with derivation, engineering mapping, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/54-spiral-matrix/Tue, 03 Feb 2026 10:01:50 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/54-spiral-matrix/Traverse a matrix in clockwise spiral order in O(mn) using boundary shrinking. Includes engineering scenarios, pitfalls, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/ai/architecture/cnn-rnn-lstm-transformer-comparison/Mon, 26 Jan 2026 16:24:56 +0800https://shio-chan-dev.github.io/jeanblog/ai/architecture/cnn-rnn-lstm-transformer-comparison/Using dependency path length and resource complexity, this article compares CNN, RNN, LSTM, and Transformer, and provides runnable examples plus a selection workflow.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/42-trapping-rain-water/Sat, 24 Jan 2026 10:40:53 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/42-trapping-rain-water/Compute trapped rain water in O(n) using two pointers and left/right maxima. Includes engineering scenarios, pitfalls, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/53-maximum-subarray/Fri, 23 Jan 2026 13:21:02 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/hot100/53-maximum-subarray/Use Kadane&#39;s algorithm to compute the maximum subarray sum in O(n). Includes engineering scenarios, pitfalls, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1437-check-if-all-ones-are-at-least-k-places-away/Thu, 22 Jan 2026 10:49:42 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1437-check-if-all-ones-are-at-least-k-places-away/One-pass check to ensure all 1s are at least k apart. Includes engineering scenarios, pitfalls, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/231-power-of-two/Wed, 21 Jan 2026 14:06:56 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/231-power-of-two/Judge whether an integer is a power of two in O(1) time using bit tricks. Includes engineering scenarios, pitfalls, and multi-language solutions.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1456-maximum-number-of-vowels-in-a-substring-of-given-length/Tue, 20 Jan 2026 13:40:45 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1456-maximum-number-of-vowels-in-a-substring-of-given-length/Use a fixed-size sliding window to compute the maximum number of vowels in O(n). Includes engineering scenarios and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/239-sliding-window-maximum/Mon, 19 Jan 2026 17:46:14 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/239-sliding-window-maximum/Solve Sliding Window Maximum in O(n) with a monotonic queue, including engineering scenarios, complexity comparisons, and multi-language implementations.https://shio-chan-dev.github.io/jeanblog/dev/c++/size_t-why-not-int-loop/Tue, 30 Dec 2025 18:12:00 +0800https://shio-chan-dev.github.io/jeanblog/dev/c++/size_t-why-not-int-loop/<h1 id="what-is-size_"><strong>What Is size_t? Why C++ Loops Prefer size_t Over int</strong></h1> <h3 id="subtitle--abstract">Subtitle / Abstract</h3> <p>When you iterate containers with a <code>for</code> loop, <code>size_t</code> is often safer and closer to the intended meaning than <code>int</code>. This post uses the ACERS structure to explain what <code>size_t</code> is, why it is used, the common pitfalls, and practical patterns for production C++.</p> <h3 id="meta">Meta</h3> <ul> <li>Reading time: 8-10 minutes</li> <li>Tags: C++, size_t, type system, loops, STL</li> <li>SEO keywords: size_t usage, size_t vs int, C++ loop initialization, size_t underflow</li> <li>Meta description: Explain size_t and why loops often use it, with safe patterns and engineering scenarios.</li> </ul> <h3 id="target-readers">Target readers</h3> <ul> <li>C++ beginners who are new to <code>size_t</code>, <code>sizeof</code>, and container <code>size()</code> return types</li> <li>Mid-level engineers who have seen <code>-Wsign-compare</code> warnings or unsigned underflow bugs</li> <li>Engineers writing cross-platform or high-performance C++</li> </ul> <h3 id="background--motivation">Background / Motivation</h3> <p>In C++ code, you often see loops like:</p>https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1512-number-of-good-pairs/Tue, 30 Dec 2025 11:40:00 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1512-number-of-good-pairs/Solve Good Pairs with one-pass hash counting, plus engineering scenarios, complexity, and multi-language solutions.https://shio-chan-dev.github.io/jeanblog/dev/go/xor-rec4-primer/Tue, 16 Dec 2025 18:12:00 +0800https://shio-chan-dev.github.io/jeanblog/dev/go/xor-rec4-primer/An intro to XOR and RC4 for Go/backend engineers, with runnable examples and safer alternatives.https://shio-chan-dev.github.io/jeanblog/alg/sorting/9.sorting-series-selection-guide/Tue, 09 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/9.sorting-series-selection-guide/Practical selection guide: decision tables by scale/distribution/stability/memory, engineering scenarios, test checklist, and common pitfalls to apply the series.https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/ai-usage-self-control/Mon, 08 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/ai-usage-self-control/How to avoid copy-paste dependence when using AI for coding: Feynman technique, deliberate practice, retrieval practice, and a practical self-check workflow.https://shio-chan-dev.github.io/jeanblog/dev/frontend/emmet-vim-guide/Mon, 08 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/dev/frontend/emmet-vim-guide/Practical Emmet notes for Vim/Neovim users: install, key mappings, runnable examples, validation checklist, and common pitfalls to 3x your page and component speed.https://shio-chan-dev.github.io/jeanblog/alg/sorting/8.sorting-series-timsort-introsort/Mon, 08 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/8.sorting-series-timsort-introsort/Explain Python/Java TimSort and C++ std::sort Introsort: triggers, stability, complexity, trade-offs, with skeletons and selection guidance.https://shio-chan-dev.github.io/jeanblog/alg/sorting/7.sorting-series-non-comparison/Sun, 07 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/7.sorting-series-non-comparison/Explain prerequisites, complexity, implementation details, and pitfalls of non-comparison sorts with multilingual examples for counting, bucket, and radix.https://shio-chan-dev.github.io/jeanblog/dev/frontend/svelte-button-config-guide/Sun, 07 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/dev/frontend/svelte-button-config-guide/Build reusable buttons in Svelte: dynamic classes, optional chaining and nullish coalescing, safe defaults, state-driven styles, accessibility, testing, and common pitfalls.https://shio-chan-dev.github.io/jeanblog/alg/sorting/6.sorting-series-heap-sort/Sat, 06 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/6.sorting-series-heap-sort/Explain heap sort principles, complexity, and engineering scenarios; compare with quick/merge; include multilingual implementations and top-k examples.https://shio-chan-dev.github.io/jeanblog/alg/sorting/5.sorting-series-quick-sort/Fri, 05 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/5.sorting-series-quick-sort/Comprehensive quicksort guide: pivot selection, three-way partitioning, tail recursion optimization, hybrid sorting practices, with multilingual implementations and engineering guidance.https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1-two-sum/Thu, 04 Dec 2025 11:10:00 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/1-two-sum/<h1 id="leetcode-1-two-sum">LeetCode 1: Two Sum</h1> <h2 id="summary">Summary</h2> <p>Find two indices such that <code>nums[i] + nums[j] = target</code>. Use a hash map for O(n) time.</p> <h2 id="approach">Approach</h2> <p>Iterate and store <code>value -&gt; index</code>. For each number <code>x</code>, check if <code>target - x</code> exists.</p> <h2 id="complexity">Complexity</h2> <ul> <li>Time: O(n)</li> <li>Space: O(n)</li> </ul> <h2 id="python-reference-implementation">Python reference implementation</h2> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-python" data-lang="python"><span style="display:flex;"><span><span style="color:#66d9ef">def</span> <span style="color:#a6e22e">two_sum</span>(nums, target): </span></span><span style="display:flex;"><span> seen <span style="color:#f92672">=</span> {} </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">for</span> i, x <span style="color:#f92672">in</span> enumerate(nums): </span></span><span style="display:flex;"><span> y <span style="color:#f92672">=</span> target <span style="color:#f92672">-</span> x </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> y <span style="color:#f92672">in</span> seen: </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> [seen[y], i] </span></span><span style="display:flex;"><span> seen[x] <span style="color:#f92672">=</span> i </span></span></code></pre></div>https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2300-successful-pairs-of-spells-and-potions/Thu, 04 Dec 2025 11:10:00 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2300-successful-pairs-of-spells-and-potions/<h1 id="leetcode-2300-successful-pairs-of-spells-and-potions">LeetCode 2300: Successful Pairs of Spells and Potions</h1> <h2 id="summary">Summary</h2> <p>For each spell, count how many potions make <code>spell * potion &gt;= success</code>. Sort potions and binary search the threshold.</p> <h2 id="approach">Approach</h2> <ul> <li>Sort potions.</li> <li>For each spell, compute <code>need = ceil(success / spell)</code>.</li> <li>Use binary search to find the first potion &gt;= need.</li> </ul> <h2 id="complexity">Complexity</h2> <ul> <li>Time: O(n log n)</li> <li>Space: O(1) extra (or O(n) if sorting a copy)</li> </ul> <h2 id="python-reference-implementation">Python reference implementation</h2> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-python" data-lang="python"><span style="display:flex;"><span><span style="color:#f92672">import</span> bisect </span></span><span style="display:flex;"><span><span style="color:#f92672">import</span> math </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span><span style="color:#66d9ef">def</span> <span style="color:#a6e22e">successful_pairs</span>(spells, potions, success): </span></span><span style="display:flex;"><span> potions <span style="color:#f92672">=</span> sorted(potions) </span></span><span style="display:flex;"><span> n <span style="color:#f92672">=</span> len(potions) </span></span><span style="display:flex;"><span> res <span style="color:#f92672">=</span> [] </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">for</span> s <span style="color:#f92672">in</span> spells: </span></span><span style="display:flex;"><span> need <span style="color:#f92672">=</span> (success <span style="color:#f92672">+</span> s <span style="color:#f92672">-</span> <span style="color:#ae81ff">1</span>) <span style="color:#f92672">//</span> s </span></span><span style="display:flex;"><span> idx <span style="color:#f92672">=</span> bisect<span style="color:#f92672">.</span>bisect_left(potions, need) </span></span><span style="display:flex;"><span> res<span style="color:#f92672">.</span>append(n <span style="color:#f92672">-</span> idx) </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> res </span></span></code></pre></div>https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2379-minimum-recolors-to-get-k-consecutive-black-blocks/Thu, 04 Dec 2025 11:10:00 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2379-minimum-recolors-to-get-k-consecutive-black-blocks/<h1 id="leetcode-2379-minimum-recolors-to-get-k-consecutive-black-blocks">LeetCode 2379: Minimum Recolors to Get K Consecutive Black Blocks</h1> <h2 id="summary">Summary</h2> <p>Given a string of &lsquo;B&rsquo; and &lsquo;W&rsquo;, find the minimum recolors to make a substring of length <code>k</code> all black.</p> <h2 id="approach">Approach</h2> <p>Use a sliding window of length <code>k</code> and count the number of whites in the window. The minimum whites across all windows is the answer.</p> <h2 id="complexity">Complexity</h2> <ul> <li>Time: O(n)</li> <li>Space: O(1)</li> </ul> <h2 id="python-reference-implementation">Python reference implementation</h2> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-python" data-lang="python"><span style="display:flex;"><span><span style="color:#66d9ef">def</span> <span style="color:#a6e22e">minimum_recolors</span>(blocks, k): </span></span><span style="display:flex;"><span> whites <span style="color:#f92672">=</span> sum(<span style="color:#ae81ff">1</span> <span style="color:#66d9ef">for</span> c <span style="color:#f92672">in</span> blocks[:k] <span style="color:#66d9ef">if</span> c <span style="color:#f92672">==</span> <span style="color:#e6db74">&#39;W&#39;</span>) </span></span><span style="display:flex;"><span> ans <span style="color:#f92672">=</span> whites </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">for</span> i <span style="color:#f92672">in</span> range(k, len(blocks)): </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> blocks[i<span style="color:#f92672">-</span>k] <span style="color:#f92672">==</span> <span style="color:#e6db74">&#39;W&#39;</span>: </span></span><span style="display:flex;"><span> whites <span style="color:#f92672">-=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> blocks[i] <span style="color:#f92672">==</span> <span style="color:#e6db74">&#39;W&#39;</span>: </span></span><span style="display:flex;"><span> whites <span style="color:#f92672">+=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> ans <span style="color:#f92672">=</span> min(ans, whites) </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> ans </span></span></code></pre></div>https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2841-maximum-sum-of-almost-unique-subarray/Thu, 04 Dec 2025 11:10:00 +0800https://shio-chan-dev.github.io/jeanblog/alg/leetcode/2841-maximum-sum-of-almost-unique-subarray/<h1 id="leetcode-2841-maximum-sum-of-almost-unique-subarray">LeetCode 2841: Maximum Sum of Almost Unique Subarray</h1> <h2 id="summary">Summary</h2> <p>Given an array, window size <code>k</code>, and threshold <code>m</code>, find the maximum sum of any length-<code>k</code> subarray that contains at least <code>m</code> distinct elements.</p> <h2 id="approach">Approach</h2> <p>Use a sliding window with a frequency map, track window sum and number of distinct values.</p> <h2 id="complexity">Complexity</h2> <ul> <li>Time: O(n)</li> <li>Space: O(n) for frequency map</li> </ul> <h2 id="python-reference-implementation">Python reference implementation</h2> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-python" data-lang="python"><span style="display:flex;"><span><span style="color:#66d9ef">def</span> <span style="color:#a6e22e">max_sum_almost_unique</span>(nums, m, k): </span></span><span style="display:flex;"><span> <span style="color:#f92672">from</span> collections <span style="color:#f92672">import</span> defaultdict </span></span><span style="display:flex;"><span> count <span style="color:#f92672">=</span> defaultdict(int) </span></span><span style="display:flex;"><span> distinct <span style="color:#f92672">=</span> <span style="color:#ae81ff">0</span> </span></span><span style="display:flex;"><span> window_sum <span style="color:#f92672">=</span> <span style="color:#ae81ff">0</span> </span></span><span style="display:flex;"><span> ans <span style="color:#f92672">=</span> <span style="color:#ae81ff">0</span> </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">for</span> i, x <span style="color:#f92672">in</span> enumerate(nums): </span></span><span style="display:flex;"><span> window_sum <span style="color:#f92672">+=</span> x </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> count[x] <span style="color:#f92672">==</span> <span style="color:#ae81ff">0</span>: </span></span><span style="display:flex;"><span> distinct <span style="color:#f92672">+=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> count[x] <span style="color:#f92672">+=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> i <span style="color:#f92672">&gt;=</span> k: </span></span><span style="display:flex;"><span> y <span style="color:#f92672">=</span> nums[i <span style="color:#f92672">-</span> k] </span></span><span style="display:flex;"><span> window_sum <span style="color:#f92672">-=</span> y </span></span><span style="display:flex;"><span> count[y] <span style="color:#f92672">-=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> count[y] <span style="color:#f92672">==</span> <span style="color:#ae81ff">0</span>: </span></span><span style="display:flex;"><span> distinct <span style="color:#f92672">-=</span> <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> i <span style="color:#f92672">&gt;=</span> k <span style="color:#f92672">-</span> <span style="color:#ae81ff">1</span> <span style="color:#f92672">and</span> distinct <span style="color:#f92672">&gt;=</span> m: </span></span><span style="display:flex;"><span> ans <span style="color:#f92672">=</span> max(ans, window_sum) </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> ans </span></span></code></pre></div>https://shio-chan-dev.github.io/jeanblog/alg/sorting/4.sorting-series-merge-sort/Thu, 04 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/4.sorting-series-merge-sort/Systematic explanation of merge sort principles, stability, space trade-offs, and engineering scenarios with Python/C/C++/Go/Rust/JS implementations and external sorting guidance.https://shio-chan-dev.github.io/jeanblog/alg/sorting/3.sorting-series-shell-sort/Wed, 03 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/3.sorting-series-shell-sort/Explain Shell sort principles, gap strategies, and engineering usage with scenarios and Python/C/C++/Go/Rust/JS implementations.https://shio-chan-dev.github.io/jeanblog/alg/sorting/2.sorting-series-on2-baseline/Tue, 02 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/2.sorting-series-on2-baseline/Systematic ACERS explanation of bubble/selection/insertion sorts: principles, stability, scenarios, and multilingual implementations with selection guidance.https://shio-chan-dev.github.io/jeanblog/alg/sorting/1.sorting-series-preface/Mon, 01 Dec 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/alg/sorting/1.sorting-series-preface/Use the ACERS template to map common sorting algorithms by scenario, complexity, stability, and engineering usage, with runnable examples and a selection checklist.https://shio-chan-dev.github.io/jeanblog/linux/linux/ufw-crowdsec-portscan/Sat, 22 Nov 2025 12:00:00 +0800https://shio-chan-dev.github.io/jeanblog/linux/linux/ufw-crowdsec-portscan/<h1 id="ufw--crowdsec-stop-malicious-port-scans">UFW + CrowdSec: Stop Malicious Port Scans</h1> <p><strong>Subtitle / Abstract:</strong> How do you protect exposed server ports? This guide shows how to move past Fail2ban regex hell and build a stable, automated, intelligent port-scan defense system.</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Developers using FRP or reverse tunnels</li> <li>Operators of cloud servers (Tencent, Alibaba, AWS, etc.)</li> <li>Linux users who want to stop port scans and SSH brute force</li> <li>People using Fail2ban who want a modern alternative</li> <li>Anyone improving personal server security</li> </ul> <hr> <h2 id="background--motivation-why-you-need-port-scan-defense">Background / Motivation: Why you need port-scan defense</h2> <p>When you run FRP (frps + frpc) or expose multiple ports, you will often see:</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/wireguard-vpn-neiwang/Thu, 20 Nov 2025 07:55:02 +0800https://shio-chan-dev.github.io/jeanblog/linux/linux/wireguard-vpn-neiwang/<h1 id="wireguard-full-guide-build-a-secure-high-speed-private-network-vpn-tutorial">WireGuard Full Guide: Build a Secure High-Speed Private Network (VPN Tutorial)</h1> <p><strong>Subtitle / Abstract:</strong> A beginner-to-intermediate WireGuard VPN guide. Learn to build a fast, secure private network and enforce a zero-exposure model where services are only reachable through VPN.</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>People who want to hide server or PC ports behind a VPN</li> <li>Users who want to reduce scanning and brute force risk</li> <li>Anyone building a private LAN or remote access to home</li> <li>Linux/Windows users, developers, and ops beginners</li> </ul> <hr> <h2 id="background-and-motivation-why-wireguard">Background and motivation: Why WireGuard?</h2> <p>If you expose ports to the public internet (SSH, databases, admin panels), you will face:</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-build-a-blog-system/Fri, 14 Nov 2025 15:04:02 +0800https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-build-a-blog-system/<h1 id="build-a-hugo-blog-with-github-pages-in-10-minutes">Build a Hugo Blog with GitHub Pages in 10 Minutes</h1> <h2 id="subtitle--abstract">Subtitle / Abstract</h2> <p>This guide takes you from zero to a deployed Hugo blog on GitHub Pages with GitHub Actions. It is beginner-friendly and explains the key moving parts.</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Hugo beginners</li> <li>Developers who want a quick technical blog</li> <li>Users of GitHub Pages and GitHub Actions</li> <li>Anyone who wants free static hosting</li> </ul> <hr> <h2 id="background--motivation">Background / Motivation</h2> <p>Common pain points when publishing a blog:</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-publish-by-hugo/Fri, 14 Nov 2025 15:01:32 +0800https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-publish-by-hugo/<h1 id="how-to-publish-with-hugo-from-markdown-to-online-blog">How to Publish with Hugo: From Markdown to Online Blog</h1> <h2 id="subtitle--abstract">Subtitle / Abstract</h2> <p>This guide explains how to create, manage, and publish Hugo posts: front matter, drafts, images, directory structure, local preview, and deployment.</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Hugo beginners</li> <li>Developers building a technical blog with Hugo</li> <li>Writers using Markdown + static sites</li> <li>Users of PaperMod, DoIt, and similar themes</li> </ul> <hr> <h2 id="background--motivation">Background / Motivation</h2> <p>After setting up a Hugo site, common questions include:</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/write-clear-issues-from-zero-to-template/Tue, 11 Nov 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/write-clear-issues-from-zero-to-template/<h2 id="title-accurate-and-keyword-rich">Title (accurate and keyword-rich)</h2> <p><strong>Write Clear Requirements with Issue Templates: A Complete Guide to GitHub Issue Forms</strong></p> <hr> <h2 id="subtitle--abstract">Subtitle / Abstract</h2> <p>This post teaches you how to configure GitHub Issue templates for feature requests and bug reports, including folder structure, YAML forms, Markdown templates, and common pitfalls. It is ideal for teams that want clearer requirements and less back-and-forth.</p> <hr> <h2 id="target-readers">Target readers</h2> <p>This article is for:</p> <ul> <li>Backend/frontend/full-stack engineers who create Issues regularly</li> <li>Leads/TLs/architects who want standardized requirement intake</li> <li>Mid-level developers familiar with GitHub but new to Issue templates</li> </ul> <p>Beginners can follow, but basic GitHub knowledge is assumed.</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/api-standards/Thu, 06 Nov 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/api-standards/<h1 id="title">Title</h1> <p><strong>How to Write a Qualified API Document: From Swagger to Modern OpenAPI</strong></p> <hr> <h2 id="subtitle--abstract">Subtitle / Abstract</h2> <p>Want developers to actually enjoy using your API? This article covers the structure, examples, and best practices of high-quality API documentation based on Swagger/OpenAPI (originally by Tony Tam).</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Beginners who want a standard API doc structure</li> <li>Mid-level developers improving maintainability</li> <li>Architects and leads defining API standards</li> </ul> <hr> <h2 id="background--motivation">Background / Motivation</h2> <p>Common problems in API docs:</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/thoughts-on-ai-systems/Fri, 31 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/thoughts-on-ai-systems/<p>For a system, a single thread should be a single assistant. We should provide each user with one assistant and optimize that assistant.</p> <p>Providing many parallel threads per user is too expensive and unnecessary.</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/configure-gitea/Tue, 28 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/configure-gitea/<h1 id="run-gitea-locally-your-private-github-with-existing-repo-import">Run Gitea Locally: Your Private GitHub (with Existing Repo Import)</h1> <p><strong>Subtitle / Abstract:</strong> This guide walks you through installing the lightweight Git server Gitea on your local machine. No root required, no system pollution. Manage, browse, and push projects like GitHub, and import existing repos.</p> <p><strong>Target readers:</strong> Personal developers, indie engineers, and small team leads with basic Git knowledge.</p> <hr> <h2 id="background--motivation">Background / Motivation</h2> <p>Many developers want:</p> <ul> <li>to host code inside a company or LAN</li> <li>to avoid cloud platforms (GitHub/Gitee)</li> <li>to have a web UI, pull requests, and code browsing</li> </ul> <p>GitLab is heavy (often multiple GB of RAM). Gitea is:</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-commit-conventions-team-efficiency/Sat, 25 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-commit-conventions-team-efficiency/<h3 id="title">Title</h3> <p>From <code>feat</code> to <code>fix</code>: master Git commit conventions for collaboration and automation</p> <hr> <h3 id="subtitle--abstract">Subtitle / Abstract</h3> <p>A practical guide to Conventional Commits. Learn commit types (<code>feat:</code>, <code>fix:</code>), write clean messages, and enable automatic changelogs and releases.</p> <hr> <h3 id="target-readers">Target readers</h3> <ul> <li><strong>Beginners</strong>: new to Git, want better commit habits.</li> <li><strong>Mid-level devs</strong>: want commits friendly to team and CI.</li> <li><strong>Leads/architects</strong>: want a consistent team standard.</li> </ul> <hr> <h3 id="background--motivation">Background / Motivation</h3> <p>Most commit messages look like:</p> <blockquote> <p>&ldquo;update code&rdquo; &ldquo;fix bug&rdquo; &ldquo;some changes&rdquo;</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-write-a-perfect-ml-document/Fri, 24 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/how-to-write-a-perfect-ml-document/<h1 id="bengio-style-ml-task-specification-from-research-to-engineering">Bengio-style ML Task Specification: From Research to Engineering</h1> <p><strong>Subtitle:</strong> How to write a reproducible, explainable, and comparable fine-tuning task document based on Yoshua Bengio&rsquo;s methodology.</p> <p><strong>Reading time:</strong> 10 minutes <strong>Tags:</strong> ML documentation, fine-tuning, technical standards, deep learning practice <strong>Audience:</strong> mid to senior ML engineers, researchers, technical writers</p> <hr> <h2 id="1-why-do-we-need-this-document">1. Why do we need this document?</h2> <p>In ML projects, teams often run fine-tuning experiments. Months later, nobody can reproduce results or explain why a learning rate or LoRA layer was chosen.</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/ping-works-ssh-fails-fake-ssh-true-vnc/Fri, 24 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/ping-works-ssh-fails-fake-ssh-true-vnc/<h1 id="ping-works-but-ssh-fails-a-real-case-of-ssh-vs-vnc">Ping Works but SSH Fails: A Real Case of SSH vs VNC</h1> <blockquote> <p><strong>Subtitle:</strong> From connection refusal to protocol identification: understand TCP, SSH, and VNC <strong>Reading time:</strong> 7 minutes <strong>Tags:</strong> network troubleshooting, SSH, VNC, Linux, remote access <strong>SEO keywords:</strong> SSH connection failed, kex_exchange_identification, VNC port 5905, RFB 003.008, SSH vs VNC</p> </blockquote> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Linux users, developers, and server admins</li> <li>Engineers learning systematic network troubleshooting</li> <li>Readers interested in SSH/VNC protocol behavior</li> </ul> <hr> <h2 id="background-and-motivation">Background and motivation</h2> <p>Have you seen this?</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/enable-ssh-without-sudo/Fri, 24 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/enable-ssh-without-sudo/<p>Below is a full draft based on your SSH startup and debugging process. It is ready for publication on a technical blog.</p> <hr> <h1 id="run-ssh-without-sudo-on-linux-user-level-sshd-guide">Run SSH Without sudo on Linux (User-Level sshd Guide)</h1> <p><strong>Subtitle / Abstract:</strong> When you have no root access in a lab or restricted server environment, how do you start SSH and access your account remotely? This guide shows how to run <code>sshd</code> in your user directory, enable key login, and connect remotely.</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/fix-sshsystem-process-start-failure/Fri, 24 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/fix-sshsystem-process-start-failure/<p><strong>Title:</strong> Run sshd Without sudo: Troubleshooting, nohup, and systemd (User-Level SSH)</p> <p><strong>Subtitle / Abstract:</strong> How to run OpenSSH as a normal user, solve common errors like &ldquo;connection refused&rdquo;, &ldquo;password auth failed&rdquo;, and <code>start-limit-hit</code>, and keep sshd alive using nohup or systemd.</p> <p><strong>Target readers:</strong> Intermediate Linux users, researchers on shared servers, and anyone who needs SSH without root.</p> <hr> <h2 id="1-background--motivation">1. Background / Motivation</h2> <p>In some lab or shared environments, regular users do not have sudo. The default sshd service cannot be started. If you need to:</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/frp-auto-start-on-ubuntu/Thu, 23 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/frp-auto-start-on-ubuntu/<h1 id="auto-start-frp-on-ubuntu-a-complete-guide">Auto-start frp on Ubuntu: A Complete Guide</h1> <p><strong>Subtitle / Abstract</strong> Use systemd to run frp (Fast Reverse Proxy) as a managed service for stable, secure, and monitored auto-start on boot.</p> <p><strong>Reading time</strong>: 8 minutes <strong>Tags</strong>: frp, intranet tunneling, systemd, auto-start, Linux, Ubuntu <strong>SEO keywords</strong>: frp auto start, Ubuntu frp config, frpc systemd, frps service, intranet tunneling <strong>Meta description</strong>: Step-by-step systemd setup for frp (frpc/frps) with config templates and troubleshooting.</p> <hr> <h2 id="target-readers">Target readers</h2> <ul> <li>Developers deploying frps on cloud servers</li> <li>Intermediate Linux users building stable home/office tunnels</li> <li>DevOps and self-hosting enthusiasts</li> </ul> <hr> <h2 id="background-and-motivation">Background and motivation</h2> <p>Many developers use <strong>frp</strong> to expose internal services (SSH, web, NAS) to the internet. The problem is that running <code>./frpc -c frpc.ini</code> manually is inconvenient and unreliable after reboot.</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/wsl-intranet-not-shared-with-windows/Wed, 22 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/wsl-intranet-not-shared-with-windows/<h1 id="windows--wsl2-port-forwarding-guide-access-flask-5000">Windows + WSL2 Port Forwarding Guide (Access Flask 5000)</h1> <h2 id="prerequisites">Prerequisites</h2> <ol> <li>You are using <strong>WSL2</strong> (Ubuntu or another Linux distro)</li> <li>The Windows host can access the LAN (Wi-Fi or Ethernet)</li> <li>A Flask service is running inside WSL2 and listening on:</li> </ol> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-python" data-lang="python"><span style="display:flex;"><span>app<span style="color:#f92672">.</span>run(host<span style="color:#f92672">=</span><span style="color:#e6db74">&#34;0.0.0.0&#34;</span>, port<span style="color:#f92672">=</span><span style="color:#ae81ff">5000</span>) </span></span></code></pre></div><blockquote> <p><code>host=&quot;0.0.0.0&quot;</code> is required; otherwise external access will fail.</p> </blockquote> <hr> <h2 id="step-1-check-the-wsl2-ip">Step 1: Check the WSL2 IP</h2> <p>In WSL2:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>ip addr show eth0 </span></span></code></pre></div><p>You should see something like:</p> <pre tabindex="0"><code>inet 172.26.209.37/20 </code></pre><blockquote> <p>Record the IP after <code>inet</code> (here: <code>172.26.209.37</code>). This is the WSL2 internal IP.</p>https://shio-chan-dev.github.io/jeanblog/linux/linux/wrk-load-testing-guide/Wed, 22 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/wrk-load-testing-guide/<h1 id="load-testing-apis-with-wrk-detailed-guide">Load Testing APIs with wrk (Detailed Guide)</h1> <blockquote> <p>This article explains how to use <code>wrk</code> on Ubuntu to stress-test backend APIs (Flask, FastAPI, Spring Boot, etc.) and interpret the results.</p> </blockquote> <hr> <h2 id="1-what-is-wrk">1. What is wrk?</h2> <p><a href="https://github.com/wg/wrk"><code>wrk</code></a> is a modern, high-performance HTTP benchmarking tool written in C. Key features:</p> <ul> <li><strong>High concurrency</strong>: thousands of concurrent connections</li> <li><strong>Multi-threaded</strong>: uses multiple CPU cores</li> <li><strong>Lua scripting</strong>: for custom headers, bodies, tokens</li> <li><strong>Faster than Apache Benchmark (ab)</strong>: lighter and more stable</li> </ul> <hr> <h2 id="2-install-wrk">2. Install wrk</h2> <p>On Ubuntu/Debian:</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/lan-git-bare-repo/Wed, 22 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/lan-git-bare-repo/<h1 id="access-a-git-bare-repo-on-windows-wsl2-from-the-lan">Access a Git Bare Repo on Windows WSL2 from the LAN</h1> <p>In development, you often need to share Git repositories across multiple machines. If you use WSL2 on Windows and want other LAN machines to access a Git bare repo inside WSL2, this guide walks you through the setup.</p> <hr> <h2 id="1-create-a-git-bare-repo-in-wsl2">1. Create a Git bare repo in WSL2</h2> <p>In WSL2, go to the target directory:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>git init --bare my_project.git </span></span></code></pre></div><ul> <li><code>my_project.git</code> is a bare repo with no working tree, only Git data.</li> <li>A bare repo behaves like a remote and can be cloned and pushed.</li> </ul> <hr> <h2 id="2-enable-ssh-in-wsl2">2. Enable SSH in WSL2</h2> <p>Other machines will access via SSH.</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-branching-workflow/Mon, 20 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-branching-workflow/<h1 id="simplified-git-branch-workflow-solo--small-team">Simplified Git Branch Workflow (Solo / Small Team)</h1> <p>This workflow is a simplified version of Git Flow. It is suitable for personal projects or small teams: structured but not heavy.</p> <hr> <h2 id="1-main-branch-long-lived">1. Main branch (long-lived)</h2> <ul> <li><strong><code>main</code></strong> <ul> <li>Always stable and release-ready</li> <li>Production deployments come from here</li> </ul> </li> </ul> <blockquote> <p>For small teams, <code>main</code> is usually enough; no need for <code>develop</code>.</p> </blockquote> <hr> <h2 id="2-feature-development-feature-branch">2. Feature development (feature branch)</h2> <ul> <li>Naming: <code>feature/&lt;feature-name&gt;</code></li> <li>Purpose: build new features, then merge back to <code>main</code></li> </ul> <p>Examples:</p>https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-bare-repo-dev-test-isolation/Mon, 20 Oct 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/notes/git-notes/git-bare-repo-dev-test-isolation/<h1 id="use-a-local-git-bare-repo-to-separate-dev-and-test-environments">Use a Local Git Bare Repo to Separate Dev and Test Environments</h1> <p>In full-stack work, a common problem is <strong>how to isolate dev and test environments</strong>. Many people host on GitHub or GitLab, but private projects may not be suitable for public hosting.</p> <p>Git is distributed. You can set up a <strong>local bare repo</strong> as a remote to move code from <strong>dev -&gt; test</strong> in one machine.</p> <hr> <h2 id="what-is-a-bare-repository">What is a bare repository?</h2> <ul> <li>A normal repo (<code>git init</code>) has a <strong>working tree + .git metadata</strong> and can be edited directly.</li> <li>A bare repo (<code>git init --bare</code>) has only Git data, no working tree. It is usually used as a <strong>remote</strong>.</li> </ul> <p>In short:</p>https://shio-chan-dev.github.io/jeanblog/dev/frontend/typescript-setup-guide/Thu, 28 Aug 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/dev/frontend/typescript-setup-guide/<h1 id="introduction">Introduction</h1> <p>For TypeScript files with the <code>.ts</code> extension, we cannot run them directly. We need to transpile TypeScript to JavaScript and then run the JavaScript output.</p> <p>There are two common approaches: upload <code>.ts</code> to the server and compile via CI, or transpile locally and upload the <code>.js</code> build to production. If you want to run and test locally during development, you can use <code>ts-node</code>, but the project still needs a build step for production.</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/ai-assistant-frontend-rebuild-ideas/Wed, 27 Aug 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/ai-assistant-frontend-rebuild-ideas/<h1 id="introduction">Introduction</h1> <p>I want to build an AI system that supports tree-shaped or graph-shaped Q&amp;A, instead of a traditional single-thread chat flow.</p> <h1 id="exploration">Exploration</h1> <h2 id="open-source-framework-research">Open-source framework research</h2> <h3 id="flowise">flowise</h3>https://shio-chan-dev.github.io/jeanblog/linux/linux/create-and-edit-mermaid-diagrams/Tue, 26 Aug 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/linux/linux/create-and-edit-mermaid-diagrams/<h1 id="introduction">Introduction</h1> <p>Mermaid is a framework for creating diagrams using code. This post shows how to install the tooling on your server and render Mermaid code into images.</p> <h1 id="steps">Steps</h1> <h2 id="install-the-renderer">Install the renderer</h2> <p>Run:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>npm install -g @mermaid-js/mermaid-cli </span></span></code></pre></div><p>Note: the CLI requires npm version &gt;= 20. It is recommended to manage npm versions with nvm.</p> <p>If you do not have nvm, install it with:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>curl -o https://raw.githubusercontent.com/nvm-sh/nvim/v0.39.4/install.sh | bash </span></span></code></pre></div><p>Restart your shell, then run:</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/mastering-paper/Tue, 26 Aug 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/mastering-paper/<h1 id="how-to-truly-master-a-paper">How to Truly Master a Paper</h1> <h1 id="conclusion">Conclusion</h1> <p>To truly master a paper, reading once is not enough. You need to decompose, verify, and reconstruct it, and then express the key points in your own words or implementation. The goal: explain the core contribution in 5 minutes, derive key formulas by hand, and reproduce a core experiment.</p> <h1 id="principles-and-background">Principles and background</h1> <p>A paper is a compressed expression of a problem. It omits background, intuition, failed attempts, and many details. Mastery requires &ldquo;decompressing&rdquo; that information into your own knowledge network: assumptions, derivations, engineering steps, and the limits of the results. Only then can you judge when to use it and when not to.</p>https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/reading-nvidia-small-models-paper/Tue, 26 Aug 2025 00:00:00 +0000https://shio-chan-dev.github.io/jeanblog/thoughts/thoughts/reading-nvidia-small-models-paper/<h1 id="what-problem-does-this-paper-solve-and-what-are-the-results">What problem does this paper solve, and what are the results?</h1> <p>We know AI systems are expanding and can solve general tasks. But many AI agent applications today target small tasks. NVIDIA argues that small language models (SLMs) are capable, more suitable, and cheaper, and should be a main direction for future agents.</p> <p>The paper discusses:</p> <ol> <li>What tasks current SLMs can handle</li> <li>Where general language ability matters</li> <li>The limits of SLMs as agents</li> </ol> <p>Conclusion: moving from LLMs to SLMs has advantages in both capability and cost.</p>