/*
 * @lc app=leetcode.cn id=268 lang=cpp
 *
 * [268] 丢失的数字
 */

// @lc code=start
class Solution {
public:
    int missingNumber(vector<int>& nums) {
        int res = 0;
        for (int i = 0; i < nums.size(); ++i) {
            res ^= nums[i];
        }
        for (int i = 0; i < nums.size() + 1; ++i) {
            res ^= i;
        }
        return res;
    }
};
// @lc code=end