Sync LeetCode submission Runtime - 139 ms (74.12%), Memory - 63.2 MB (40.37%)

Author: jimit105

0325-maximum-size-subarray-sum-equals-k/README.md

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+<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the maximum length of a </em><span data-keyword="subarray"><em>subarray</em></span><em> that sums to</em> <code>k</code>. If there is not one, return <code>0</code> instead.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,-1,5,-2,3], k = 3
+<strong>Output:</strong> 4
+<strong>Explanation:</strong> The subarray [1, -1, 5, -2] sums to 3 and is the longest.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [-2,-1,2,1], k = 1
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> The subarray [-1, 2] sums to 1 and is the longest.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>5</sup></code></li>
+	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
+	<li><code>-10<sup>9</sup>&nbsp;&lt;= k &lt;= 10<sup>9</sup></code></li>
+</ul>

0325-maximum-size-subarray-sum-equals-k/solution.py

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+# Approach: Prefix Sum + Hash Map
+
+# Time: O(n)
+# Space: O(n)
+
+class Solution:
+    def maxSubArrayLen(self, nums: List[int], k: int) -> int:
+        prefix_sum = longest_subarray = 0
+        indices = {}
+
+        for i, num in enumerate(nums):
+            prefix_sum += num
+
+            if prefix_sum == k:
+                longest_subarray = i + 1
+
+            if prefix_sum - k in indices:
+                longest_subarray = max(longest_subarray, i - indices[prefix_sum - k])
+
+            if prefix_sum not in indices:
+                indices[prefix_sum] = i
+
+        return longest_subarray
+