Feat: 128. Longest Consecutive Sequence

Author: HC-kang

longest-consecutive-sequence/HC-kang.ts

@@ -1,3 +1,24 @@
+/**
+ * https://leetcode.com/problems/longest-consecutive-sequence/
+ * T.C.: O(n)
+ * S.C.: O(n)
+ */
 function longestConsecutive(nums: number[]): number {
-  return 0;
+  const numSet = new Set(nums);
+  let max = 0;
+
+  for (const num of numSet) {
+    if (numSet.has(num - 1)) {
+      continue;
+    }
+
+    let count = 0;
+    while (numSet.has(num + count)) {
+      count++;
+    }
+
+    if (count > max) max = count;
+  }
+
+  return max;
 }