Sliding Window Maximum

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Problem

Given an array and a window size k, return an array of the maximum value in each sliding window of size k as it moves from the very left of the array to the very right.

Examples

Example 1

Input:nums = [1,3,-1,-3,5,3,6,7], k = 3

Output:[3,3,5,5,6,7]

Example 2

Input:nums = [1], k = 1

Output:[1]

Constraints

1 <= k <= nums.length <= 10^5

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How to approach it: the Sliding Window pattern

A window — a contiguous subarray or substring — expands and shrinks as it moves across the input, so you track a running condition instead of recomputing it from scratch for every possible window.

Look for this pattern when

The problem asks for the longest/shortest/best contiguous subarray or substring meeting a condition.
Brute force would recompute a sum or count for every possible window — a sign that work can be shared between overlapping ranges.

Read the full Sliding Window guide →

Video walkthroughs

Original problem on LeetCode ↗