LeetCode-268. Missing Number

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.

Example 1:

Input: [3,0,1]
Output: 2

Example 2:

Input: [9,6,4,2,3,5,7,0,1]
Output: 8

Note:
Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?

    public int missingNumber(int[] nums) {
        int re = 0;
        for(int i =0;i<nums.length;i++){
            re = re^i^nums[i];//x^a^a =x;x^0=x
        }
        re = re^nums.length;
        return re;
    }