Update 239-Sliding-Window-Maximum.py

Author: Ahmad-A0

Diff for: python/239-Sliding-Window-Maximum.py

@@ -4,7 +4,7 @@ def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
         q = collections.deque() # index
         l = r = 0
         # O(n) O(n)
-        while l < len(nums):
+        while r < len(nums):
             # pop smaller values from q
             while q and nums[q[-1]] < nums[r]:
                 q.pop()