1class Solution:
2    def missingNumber(self, nums):
3        n = len(nums)
4        total = n * (n + 1) // 2
5        return total - sum(nums)
6
7# Usage
8nums = [3, 0, 1]
9sol = Solution()
10print(f"Missing number: {sol.missingNumber(nums)}")

1#include <iostream>
#include <vector>
using namespace std;

int missingNumber(vector<int>& nums) {
    int xor_result = 0;
    for (int i = 0; i < nums.size(); i++) {
        xor_result ^= i ^ nums[i];
    }
    xor_result ^= nums.size();
    return xor_result;
}

int main() {
    vector<int> nums = {3, 0, 1};
    cout << "Missing number: " << missingNumber(nums) << endl;
    return 0;
}