CSES-1643 Maximum Subarray Sum

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

#define pb push_back
#define fi first
#define se second
#define INF LONG_LONG_MAX/1000
#define WA() cin.tie(0)->sync_with_stdio(0)
#define all(x) (x).begin(), (x).end()
#define int long long
#define PII pair<int, int>

signed main() { WA();
    int n, i, sum = 0, mx = -1e9;
    cin >> n;

    while (n--) {
        cin >> i;
        sum += i;
        mx = max(mx, sum);
        if (sum < 0) sum = 0;
    }
    cout << mx;
}