Sync LeetCode submission Runtime - 19 ms (89.80%), Memory - 19.2 MB (46.65%)

Author: jimit105

0594-longest-harmonious-subsequence/README.md

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+<p>We define a harmonious array as an array where the difference between its maximum value and its minimum value is <b>exactly</b> <code>1</code>.</p>
+
+<p>Given an integer array <code>nums</code>, return the length of its longest harmonious <span data-keyword="subsequence-array">subsequence</span> among all its possible subsequences.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [1,3,2,2,5,2,3,7]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">5</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>The longest harmonious subsequence is <code>[3,2,2,2,3]</code>.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [1,2,3,4]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">2</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>The longest harmonious subsequences are <code>[1,2]</code>, <code>[2,3]</code>, and <code>[3,4]</code>, all of which have a length of 2.</p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [1,1,1,1]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">0</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>No harmonic subsequence exists.</p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
+	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
+</ul>

0594-longest-harmonious-subsequence/solution.py

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+# Approach: Counter
+
+# Time: O(n)
+# Space: O(n)
+
+from collections import Counter
+
+class Solution:
+    def findLHS(self, nums: List[int]) -> int:
+        freq = Counter(nums)
+        max_length = 0
+
+        for num in freq:
+            if num + 1 in freq:
+                max_length = max(max_length, freq[num] + freq[num + 1])
+
+        return max_length
+