Apple Division

input/code.cpp: In function 'void solve()':
input/code.cpp:27:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |   for (int i = 0; i < f.size(); i++) {
      |                   ~~^~~~~~~~~~

#include <bits/stdc++.h>
using namespace std;

vector<int>f;

void backtracking (int ans, int a[21], int i, int n) {
    if (i == n) {
        //cout << ans << ' ';
        f.push_back(ans);
        return;
    } 
    
    backtracking(ans + a[i], a, i + 1, n);
    backtracking(ans - a[i], a, i + 1, n);

}

void solve() {
  int n;
  int a[20];
  int ans = 9999999;
  cin >> n;
  for (int i = 0; i < n; i++) {
      cin >> a[i];
  }
  backtracking(0, a, 0, n);
  for (int i = 0; i < f.size(); i++) {
      if (f[i] >= 0) {
          if (f[i] < ans) ans = f[i];
      }
  }
  cout << ans;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    solve();

    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

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: ACCEPTED