Sliding Window

A sliding window keeps a contiguous range over an array or string and expands or shrinks its two edges to maintain a constraint, turning an O(n²) scan of every subarray into a single O(n) pass. Use it for longest / shortest / contains questions about a contiguous subarray or substring.

15 LeetCode problems solved with the Sliding Window pattern. Practice them with spaced repetition so the pattern sticks.

• Count the Number of Good SubarraysMEDIUM · O(n)
• Find All Anagrams in a StringMEDIUM · O(n)
• Longest Continuous Increasing SubsequenceEASY · O(n)
• Longest Repeating Character ReplacementMEDIUM · O(n)
• Longest Subarray of 1's After Deleting One ElementMEDIUM · O(n)
• Longest Substring Without Repeating CharactersMEDIUM · O(n)
• Max Consecutive Ones IIIMEDIUM · O(n)
• Maximum Average Subarray IEASY · O(n)
• Maximum Erasure ValueMEDIUM · O(n)
• Maximum Number of Vowels in a Substring of Given LengthMEDIUM · O(n)
• Minimum Size Subarray SumMEDIUM · O(n)
• Minimum Window SubstringHARD · O(m + n)
• Permutation in StringMEDIUM · O(n)
• Sliding Window MaximumHARD · O(n)
• Substring with Concatenation of All WordsHARD · O(n * L)