Maximum sum

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

int main() {
	ll n;
	cin >> n;
	vector<ll> a;
	for (ll i=0; i<n; i++) {
		ll b;
		cin >> b;
		a.push_back(b);
	}

	ll rs = 0, mi = 0, mv = -999;
	for (ll i=0; i<n; i++) {
		rs += a[i];
		if (rs > mv) {
			mv = rs;
			mi = i;
		}
	}
	
	rs = 0, mv = -999;
	ll ni = 0;
	for (ll i=n-1; i>=0; i--) {
		rs += a[i];
		if (rs > mv) {
			mv = rs;
			ni = i;
		}
	}
	rs = 0;
	for (ll i=ni; i<=mi; i++) {
		rs += a[i];
	}
	cout << rs;
}

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: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: ACCEPTED