def next_greater_element(nums):
    res = []
    stack = collections.deque()
    for i in range(len(nums) - 1, -1, -1):
        while stack and stack[-1] <= nums[i]:
            s.pop()  # remove smaller numbers
        # some ops
        res[i] = s[-1] if stack else -1
        stack.append(nums[i])  # push
    return res

def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
    def push_queue(i):
        if window and window[0] == i-k:
            window.popleft()

        while window and nums[i] > nums[window[-1]]:
            window.pop()
        window.append(i)
        
    window = collections.deque()
    res = []
    for i in range(len(nums)):
        if (i < k - 1):  # initialize first (k-1)
            push_queue(i)
        else:  # move window
            push_queue(i)
            res.append(nums[window[0]])
    return res

class MonoQueue:
    def __init__(self):
        self.data = collections.deque()

    def push(self, n):
        while data and data[0] < n:
            data.pop()
        data.append(n)

    def max(self):
        return data[0]

    def pop(n):
        if data and data[0] == n:
            data.popleft()


def max_sliding_win(nums, k):
    window = MonoQueue()
    res = []
    for i in range(len(nums)):
        window.push(nums[i])
        if i >= k:
            res.append(window.max())
            window.pop(nums[i - k + 1])