Add 128-Longest-consecutive-sequence.js

Author: IbuAR

javascript/128-Longest-consecutive-sequence.js

@@ -0,0 +1,24 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function (nums) {
+
+    const set = new Set(nums);
+    let max = 0;
+
+    for (let i = 0; i < nums.length; i++) {
+        const num = nums[i];
+        if (set.has(num - 1)) continue;
+
+        let currentMax = 1;
+        while (set.has(num + currentMax)) {
+            currentMax++;
+        }
+
+        if (currentMax > max) max = currentMax;
+    }
+
+    return max;
+
+};