268. Missing Number

Problem:
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

Analysis:
Similar to single number. If we have [0,1,3], then XOR with the complete set [0,1,2,3], we can get 2.
Solution:

class Solution {
    public int missingNumber(int[] nums) {
        int res = nums.length;
        for (int i = 0; i < nums.length; i++) {
            res ^= i ^ nums[i];
        }
        return res;
    }
}