Missing Coin Sum

#include <bits/stdc++.h>
 
using namespace std;
 
/*
 
créeons Ek = {x1, x2, ..., xk}
tel que pour tout y dans [x1, xk],
on peut créer y avec les éléments de Ek
 
 
 
*/
 
int main() {
 
    int N;
    cin >> N;
 
    vector<int> X(N);
    for (int i = 0; i < N; i++)
        cin >> X[i];
    
    sort(X.begin(), X.end());
 
    if (X[0] != 1) {
        cout << 1 << endl;
        return 0;
    }
 
    long long sum = 1;
 
    for (int k = 1; k < N; k++) {
        int coin_to_add = X[k];
        if (coin_to_add > sum + 1) {
            cout << sum + 1 << endl;
            return 0;
        } else {
            sum += coin_to_add;
        }
    }
 
    cout << sum+1 << endl;
    return 0;
 
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED