Sliding Window Maximum - Codey

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Description Submissions Solution

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Solution

Updated: 2026-02-23

Idea

Maintain a monotonic deque of indices whose values are in decreasing order.

Approach

For each index i:

Pop from the back while the new value is larger (it dominates smaller ones).
Push i.
Pop from the front if it’s outside the window.
The front is the max for the current window.

Why it works

The deque always contains only candidates for the maximum, ordered so the max is at the front.

Code

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Complexity

Time: O(n)

Space: O(k)

Solution

Updated: 2026-02-23

Idea

Maintain a monotonic deque of indices whose values are in decreasing order.

Approach

For each index i:

Pop from the back while the new value is larger (it dominates smaller ones).
Push i.
Pop from the front if it’s outside the window.
The front is the max for the current window.

Why it works

The deque always contains only candidates for the maximum, ordered so the max is at the front.

Code

Loading...

Complexity

Time: O(n)

Space: O(k)