contains duplicate solution

Author: heesun-task

contains-duplicate/heesun-task.js

@@ -0,0 +1,26 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+ /*
+    Goal: return true if duplicated #, false if no duplicated number
+
+    Plan:
+    - create a Set
+    - loop num in nums
+        - num exists in the Set -> return true
+        - not exsits ->  add the num in the Set, continue to the next loop
+    - return false 
+
+    space complexity: O(n)
+    time complexity: O(n)
+  */
+var containsDuplicate = function(nums) {
+    const seen = new Set();
+
+    for(const num of nums) {
+        if (seen.has(num)) return true;
+        seen.add(num);
+    }
+    return false; 
+};