LeetCode Pattern

Learn the sliding window technique to efficiently solve array and string problems. Master fixed-size and variable-size window patterns.

Master the two-pointer technique for arrays, strings, and linked lists. Learn opposite direction, fast/slow, and in-place manipulation patterns.

Master prefix sum techniques for range queries, subarray problems, and matrix operations. Learn 1D, 2D, hash map combinations, and difference arrays.

Master hash map patterns for O(1) lookup problems. Learn frequency counting, two sum, grouping, index mapping, and prefix sum combinations.

Master monotonic stack and queue patterns for next greater/smaller element, histogram, and sliding window maximum problems. Learn O(n) optimization techniques.

Master binary search patterns for sorted arrays, rotated arrays, 2D matrices, and optimization problems. Learn O(log n) search techniques and binary search on answer.

Master greedy algorithm patterns for interval scheduling, sorting, state tracking, and optimization problems. Learn when greedy works vs when DP is required, with rigorous proofs.