@@ -0,0 +1,257 @@
+public class Solution %7B%0A    public int missingNumber(int%5B%5D nums) %7B%0A        int n = nums.length;%0A        int sum = 0;%0A        %0A        for (int i = 0; i %3C n; i++) %7B%0A            sum += nums%5Bi%5D;%0A        %7D%0A        %0A        return (1 + n) * n / 2 - sum;%0A    %7D%0A%7D%0A

Create MissingNum_001.java