added Function

Author: mauricechouam

Find All Numbers Disappeared in an Array/code.js

@@ -0,0 +1,19 @@
+/*
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var findDisappearedNumbers = function(nums) {
+    
+    const result = new Array(nums.length);
+  
+  for(let i = 0; i < nums.length; i++){
+      result[nums[i]-1] = nums[i];
+  }
+
+  for(let i = 0; i < nums.length; i++) {
+      if(!result[i]) result.push(i+1);
+  }
+  
+  return result.splice(nums.length);
+};
+