Sliding window maximum

Sliding window maximum.py

from collections import deque  


def maxSlidingWindow(nums, window_size):

    start, ans = 0, []
    q = deque();
    
    for end in range(len(nums)):
        while q and nums[end] > nums[q[-1]]: q.pop()
        q.append(end)            

        if end >= window_size-1:    
            ans.append(nums[q[0]])
            start += 1
            while q and q[0] < start: q.popleft()


    return ans
                

• When end pointer moves forward: add element to queue, ensuring the max value stays at 0th index
• When start pointer moves forward: remove from queue, which were processed in previous windows. i.e remove all indexes less than first index in queue