dsa5 min read
Word Search — LC 79 DFS + Backtracking on Grid
LeetCode 79 is a FAANG grid backtracking classic. Use DFS with in-place visited marking to search a word path through a board in O(m*n*4^L).
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dsa4 min read
Increasing Triplet Subsequence — LC 334 Greedy O(1) Space
LeetCode 334 looks like an LIS problem but ships in O(n) time and O(1) space using two greedy trackers. A classic FAANG follow-up to standard LIS.
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dsa5 min read
4Sum — LC 18 Two Loops Plus Two Pointers
LeetCode 18 generalizes 3Sum to four numbers with target sum. Sort, fix two indices, and run two pointers — O(n^3) time and clean duplicate handling.
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dsa4 min read
Jump Game II — LC 45 Greedy BFS Layer Tracking
LeetCode 45 asks for the minimum number of jumps to reach the end. A greedy BFS-layer approach gives O(n) time and O(1) space — a FAANG favorite.
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dsa6 min read
Gas Station — Greedy One-Pass Circuit Feasibility [LC 134]
LeetCode 134 — asked at Amazon, Google, and Microsoft. Find the unique valid starting station in a circular gas route using a two-insight greedy: global feasibility check plus a local reset that eliminates O(n) candidates at once, giving O(n) time and O(1) space.
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