Maximum sum

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

const ll INTMIN = -2'000'000'000;

int main() {
	ll n;
	cin >> n;
	vector<ll> a;
	ll maxx = INTMIN;
	a.push_back(INTMIN);
	for (ll i=0; i<n; i++) {
		ll b;
		cin >> b;
		ll c = max(b, a[i]+b);
		maxx = max(c, maxx);
		a.push_back(max(b, a[i]+b));

	}
	cout << maxx;
}

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: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED