Create number_disappeared_in_array.js

Author: TheCoderSingh

number_disappeared_in_array.js

@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var findDisappearedNumbers = function(nums) {
+    let result = [];
+    let origLength = nums.length;
+    let unique = new Set(nums);
+
+    for(let i = 1; i <= origLength; i++) {
+        if(!unique.has(i)) {
+            result.push(i);
+        }
+    }
+
+    return result;
+};