O(n)求一个数组中连续区间和的最大值

int n, a[5000];
int main(){
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)cin >> a[i];
    ll cur = 0, ans = 0, l, r, tl = 1;
    for (int i = 1; i <= n; i++){
        if (cur<0){
            cur = 0;
            tl = i;
        }
        cur += a[i];
        if (cur>ans){
            ans = cur;
            r = i;
            l = tl;
        }
    }
    cout << ans << ' ' << l << ' ' << r << endl;
    return 0;
}