Sync LeetCode submission Runtime - 124 ms (99.00%), Memory - 30.9 MB (84.67%)

Author: jimit105

0239-sliding-window-maximum/README.md

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+<p>You are given an array of integers&nbsp;<code>nums</code>, there is a sliding window of size <code>k</code> which is moving from the very left of the array to the very right. You can only see the <code>k</code> numbers in the window. Each time the sliding window moves right by one position.</p>
+
+<p>Return <em>the max sliding window</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,3,-1,-3,5,3,6,7], k = 3
+<strong>Output:</strong> [3,3,5,5,6,7]
+<strong>Explanation:</strong> 
+Window position                Max
+---------------               -----
+[1  3  -1] -3  5  3  6  7       <strong>3</strong>
+ 1 [3  -1  -3] 5  3  6  7       <strong>3</strong>
+ 1  3 [-1  -3  5] 3  6  7      <strong> 5</strong>
+ 1  3  -1 [-3  5  3] 6  7       <strong>5</strong>
+ 1  3  -1  -3 [5  3  6] 7       <strong>6</strong>
+ 1  3  -1  -3  5 [3  6  7]      <strong>7</strong>
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1], k = 1
+<strong>Output:</strong> [1]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
+	<li><code>1 &lt;= k &lt;= nums.length</code></li>
+</ul>

0239-sliding-window-maximum/solution.py

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+# Approach: Monotonic Deque
+
+# Time: O(n)
+# Space: O(k)
+
+from collections import deque
+
+class Solution:
+    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
+        dq = deque()
+        res = []
+
+        for i in range(k):
+            while dq and nums[i] >= nums[dq[-1]]:
+                dq.pop()
+            dq.append(i)
+
+        res.append(nums[dq[0]])
+
+        for i in range(k, len(nums)):
+            if dq and dq[0] == i - k:
+                dq.popleft()
+            while dq and nums[i] >= nums[dq[-1]]:
+                dq.pop()
+
+            dq.append(i)
+            res.append(nums[dq[0]])
+
+        return res
+