feat: missing-number

Author: minji-go

missing-number/minji-go.java

@@ -1,19 +1,16 @@
-/*
-    Problem: https://leetcode.com/problems/missing-number/
-    Description: return the only number in the range that is missing from the array.
-    Concept: Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting
-    Time Complexity: O(N), Runtime 0ms
-    Space Complexity: O(1), Memory 45.71MB
-*/
+/**
+ * <a href="https://leetcode.com/problems/missing-number/">week11-1. missing-number</a>
+ * <li>Description: Return the only number in the range that is missing from the array</li>
+ * <li>Topics: Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting </li>
+ * <li>Time Complexity: O(N), Runtime 0ms       </li>
+ * <li>Space Complexity: O(1), Memory 45.67MB   </li>
+ */
 class Solution {
     public int missingNumber(int[] nums) {
-        int n = nums.length;
-        int missing = n;
-
-        for(int i=0; i<n; i++){
-            missing ^= i;
-            missing ^= nums[i];
+        int sum = (nums.length) * (nums.length + 1) / 2;
+        for (int i = 0; i < nums.length; i++) {
+            sum -= nums[i];
         }
-        return missing;
+        return sum;
     }
 }