Sorted Array

Subtitle / Summary This problem is a compact exercise in boundary counting. Because the array is already sorted, you do not count negatives and positives one by one; you find where zero starts and where zero ends, then compute both counts from those boundaries. Reading time: 10-12 min Tags: binary search, counting, sorted array, boundaries SEO keywords: Maximum Count of Positive Integer and Negative Integer, LeetCode 2529, boundary counting Meta description: Use lower-bound and upper-bound binary search around zero to count negatives and positives in a sorted array, with correctness reasoning, engineering scenarios, and runnable implementations in six languages. Target Readers Learners practicing boundary search beyond exact-match lookup Engineers who count segments in sorted data Interview candidates learning how lower and upper bounds produce counts Background / Motivation The input is already sorted. That changes the problem completely. ...

Subtitle / Summary This problem is the standard upgrade from “find one target” to “find the whole target block.” The clean solution is not a special-case binary search, but two boundary searches: lower bound for the start and upper bound for the end. Reading time: 12-14 min Tags: binary search, lower bound, upper bound, range query SEO keywords: Search Range, lower bound, upper bound, LeetCode 34 Meta description: Use lower-bound and upper-bound binary search to find the first and last positions of a target in a sorted array, with pitfalls, engineering scenarios, and runnable implementations in six languages. Target Readers Learners who already know basic binary search but struggle with boundary problems Engineers who query sorted logs, timestamps, or grouped IDs Interview candidates who want one reusable range-search template Background / Motivation Finding a single target in a sorted array is the easy version. Real systems often need the full range: ...

Subtitle / Summary Search Insert Position is the cleanest lower-bound problem in LeetCode. If you can reliably find the first index where nums[i] >= target, you already have the core template for insert positions, range starts, and many boundary-search problems. Reading time: 10-12 min Tags: binary search, lower bound, sorted array SEO keywords: Search Insert Position, lower bound, binary search, LeetCode 35 Meta description: Lower-bound binary search for Search Insert Position, with boundary reasoning, pitfalls, engineering scenarios, and runnable implementations in Python, C, C++, Go, Rust, and JavaScript. Target Readers Learners who know basic binary search but still hesitate on boundary handling Engineers who insert or locate values in sorted tables Interview candidates who want one reusable lower-bound template Background / Motivation This problem looks simple because the output is a single index. The real lesson is deeper: ...

Subtitle / Summary This problem is a textbook upper-bound search with one extra twist: wrap-around. Once you can find the first character > target, the rest is just handling the “no answer inside the array” case by returning the first element. Reading time: 10-12 min Tags: binary search, upper bound, characters, wrap-around SEO keywords: Find Smallest Letter Greater Than Target, upper bound, LeetCode 744 Meta description: Use upper-bound binary search and wrap-around handling to solve LeetCode 744, with correctness reasoning, pitfalls, engineering scenarios, and runnable code in six languages. Target Readers Learners who already know lower bound and want to master upper bound Engineers who search the next greater value in a sorted cyclic list Interview candidates practicing boundary-style binary search Background / Motivation At first glance, this looks like a character problem. It is actually a boundary problem: ...