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Author: Annahcj

Sorting/594.longest-harmonious-subsequence.js

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+// 594. Longest Harmonious Subsequence
+// We define a harmonious array as an array where the difference between its maximum value and its minimum value is exactly 1.
+// Given an integer array nums, return the length of its longest harmonious subsequence among all its possible subsequences.
+
+
+// Solution: Sorting & Sliding Window
+
+// Sort nums, then maintain a sliding window where difference between first and last item is no greater than 1.
+// Record the maximum length of the sliding window.
+
+// Time Complexity: O(n log(n)) 45ms
+// Space Complexity: O(log(n)) 60MB
+function findLHS(nums) {
+  nums.sort((a, b) => a - b);
+  const n = nums.length;
+  let lhs = 0;
+  for (let j = 0, i = 0; j < n; j++) {
+    while (nums[j] - nums[i] > 1) i++;
+    if (nums[j] - nums[i] > 0) {
+      lhs = Math.max(lhs, j - i + 1);
+    }
+  }
+  return lhs;
+};
+
+// Three test cases
+console.log(findLHS([1,3,2,2,5,2,3,7])) // 5
+console.log(findLHS([1,2,3,4])) // 2
+console.log(findLHS([1,1,1,1])) // 0