Feat: 268. Missing Number

Author: HC-kang

missing-number/HC-kang.ts

@@ -1,3 +1,10 @@
+/**
+ * https://leetcode.com/problems/missing-number/
+ * T.C.: O(n)
+ * S.C.: O(1)
+ */
 function missingNumber(nums: number[]): number {
-  return 0;
+  let sum = nums.length; // i for 0 to n-1. So, n is missing.
+  for (let i = 0; i < nums.length; i++) sum = sum + i - nums[i];
+  return sum;
 }