Maximum sum

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

const int N = 2e5 + 2;

int main () {
    int n; cin >> n;
    int ar[N]; ar[0] = 0;
    int cum[N]; cum[0] = 0;
    for(int i = 1; i <= n; i++) cin >> ar[i];
    for(int i = 1; i <= n; i++) cum[i] = cum[i-1] + ar[i];
    // for(int i = 1; i <= n; i++) cout << cum[i] << ' ';
    // cout  << '\n';
    
    int prefix=0;
    int best = cum[n] - prefix;
    for(int i = 1; i <= n; i++) {
        prefix = min(cum[i], prefix);
        best = max(best, cum[i]-prefix);
    }
    // cout << '\n';

    cout << best << '\n';
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: ACCEPTED

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER