All Topics
Sliding Window & Two Pointers
Fixed and variable-width windows for substring, subarray, and two-pointer problems
0/34 solved
Fixed Window
Process subarrays of exact size K using a sliding window
O(n) O(1)
Approach
Build initial window of size K. Slide right: add new element, remove leftmost. At each position, compute the required metric (sum, max, min, average). This gives O(n) instead of O(n*K).
How to Recognize
1
Problem specifies a fixed window size K
2
Need max/min/sum of all subarrays of size K
3
Phrases like 'subarray of size K', 'K consecutive elements'
4
Window size doesn't change as it slides
Pro Tips
Initialize window with first K elements, then slide by adding right and removing left
Use a deque for max/min in window in O(1) amortized
Don't forget edge case: array length < K
8
Total
5
Easy
2
Medium
1
Hard
Time
O(n)
Space
O(1)