LeetCode-in-TypeScript.github.io

239. Sliding Window Maximum

Hard

You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.

Return the max sliding window.

Example 1:

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

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

Explanation:

Window position        Max
---------------       -----
[1 3 -1] -3 5 3 6 7     3
1 [3 -1 -3] 5 3 6 7     3
1 3 [-1 -3 5] 3 6 7     5
1 3 -1 [-3 5 3] 6 7     5
1 3 -1 -3 [5 3 6] 7     6
1 3 -1 -3 5 [3 6 7]     7 

Example 2:

Input: nums = [1], k = 1

Output: [1]

Example 3:

Input: nums = [1,-1], k = 1

Output: [1,-1]

Example 4:

Input: nums = [9,11], k = 2

Output: [11]

Example 5:

Input: nums = [4,-2], k = 2

Output: [4]

Constraints:

Solution

function maxSlidingWindow(nums: number[], k: number): number[] {
    const result: number[] = []
    // Maintain indices in the deque
    const deque: number[] = []
    for (let i = 0; i < nums.length; i++) {
        // Remove indices that are out of the window
        while (deque.length > 0 && deque[0] <= i - k) {
            deque.shift()
        }
        // Remove indices of smaller elements as they are no longer candidates for maximum
        while (deque.length > 0 && nums[i] >= nums[deque[deque.length - 1]]) {
            deque.pop()
        }
        // Add the current index to the deque
        deque.push(i)
        // Add the maximum element for the current window to the result
        if (i >= k - 1) {
            result.push(nums[deque[0]])
        }
    }
    return result
}

export { maxSlidingWindow }