Stage 1 · Code
Two Pointers & Sliding Window
Timed Problem Set
10 curated window and pointer problems — 40 minutes, increasing difficulty.
10 min readLeetCode Patterns for InterviewsCode
Drill instructions
Set a 40-minute timer. Identify the window type (fixed/dynamic, min/max) before coding. If stuck for 8 minutes, read the hint.
Problems
#167Two Sum IIEasyOpposite pointers on sorted · O(n) time · O(1) space#153SumMediumSort + two pointer · O(n²) time · O(1) space#3Longest Substring Without Repeating CharactersMediumDynamic window · O(n) time · O(n) space#567Permutation in StringMediumFixed window freq match · O(n) time · O(1) space#76Minimum Window SubstringHardDynamic window — minimum covering · O(n) time · O(n) space#424Longest Repeating Character ReplacementMediumDynamic window with max freq tracking · O(n) time · O(1) space#643Maximum Average Subarray IEasyFixed window · O(n) time · O(1) space#239Sliding Window MaximumHardFixed window with monotonic deque · O(n) time · O(k) space#11Container With Most WaterMediumOpposite pointers greedy · O(n) time · O(1) space#42Trapping Rain WaterHardTwo pointer with running max · O(n) time · O(1) space
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