https://shio-chan-dev.github.io/jeanblog/tags/hot100/Recent content in Hot100 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/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/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->Ln->L1->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/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/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/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's algorithm to compute the maximum subarray sum in O(n). Includes engineering scenarios, pitfalls, and multi-language implementations.