sliding_window_max.py

"""
Given an array 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.

For example,
Given nums = [1,3,-1,-3,5,3,6,7], and k = 3.

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
Therefore, return the max sliding window as [3,3,5,5,6,7].
"""
import collections


def max_sliding_window(nums, k):
    """
    :type nums: List[int]
    :type k: int
    :rtype: List[int]
    """
    if not nums:
        return nums
    queue = collections.deque()
    res = []
    for num in nums:
        if len(queue) < k:
            queue.append(num)
        else:
            res.append(max(queue))
            queue.popleft()
            queue.append(num)
    res.append(max(queue))
    return res