Sliding Window Maximum

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]

Constraints:

• 1 <= nums.length <= 105
• -104 <= nums[i] <= 104
• 1 <= k <= nums.length

SOLUTION:

import heapq

class Solution:
    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
        n = len(nums)
        maxes = []
        deleted = {}
        window = [-num for num in nums[:k]]
        heapq.heapify(window)
        maxes.append(-window[0])
        for i in range(0, n - k):
            heapq.heappush(window, -nums[i + k])
            deleted[-nums[i]] = deleted.get(-nums[i], 0) + 1
            curr = window[0]
            while curr in deleted:
                heapq.heappop(window)
                deleted[curr] -= 1
                if deleted[curr] == 0:
                    del deleted[curr]
                curr = window[0]
            maxes.append(-curr)
        return maxes