Problem p03850 (C++)

Buggy submission (status: Time Limit Exceeded):
/*input
5
1 - 20 - 13 + 14 - 5
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i, n) for (int i = 1; i <= n; i++)
#define RED(i, n) for (int i = n; i > 0; i--)
#define REPS(i, n) for (int i = 1; (i * i) <= n; i++)
#define REP(i, n) for (int i = 0; i < (int)n; i++)
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define REPD(i, n) for (int i = n - 1; i >= 0; i--)
#define FORD(i, a, b) for (int i = a; i >= b; i--)

#define all(v) v.begin(), v.end()
#define pii pair<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr)                                                             \
  for (auto it = arr.begin(); it != arr.end(); ++it)                           \
    cout << *it << " ";                                                        \
  cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x, y) cout << x << " " << y << endl;
#define debug3(x, y, z) cout << x << " " << y << " " << z << endl;

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;

const int INF = 1e18 + 1;
const int MOD = 1e9 + 7;
const double PI = 3.14159265358979323846264338;

int raise(int a, int n, int m = MOD) {
  if (n == 0)
    return 1;
  if (n == 1)
    return a;
  int x = 1;
  x *= raise(a, n / 2, m);
  x %= m;
  x *= x;
  x %= m;
  if (n % 2)
    x *= a;
  x %= m;
  return x;
}

int floor1(int n, int k) {
  if (n % k == 0 || n >= 0)
    return n / k;
  return (n / k) - 1;
}

int ceil1(int n, int k) { return floor1(n + k - 1, k); }

const int N = 1e5 + 1;
int prefr[N];
int prefa[N];
int n;
int a[N];
int op[N];

void solve() {
  cin >> n;
  op[1] = 1;
  cin >> a[1];
  prefr[1] = prefa[1] = a[1];
  for (int i = 2; i <= n; i++) {
    char o;
    cin >> o;
    op[i] = -1 + 2 * (o == '+');
    cin >> a[i];
    prefr[i] = prefr[i - 1] + a[i] * op[i];
    prefa[i] = prefa[i - 1] + a[i];
  }
  int ans = prefr[n];
  for (int i = 1; i <= n; i++) {
    if (op[i] == -1) {
      for (int j = i + 1; j <= n; j++) {
        if (op[j] == -1) {
          int one = prefr[i - 1] + prefa[n] - prefa[j - 1] -
                    (prefa[j - 1] - prefa[i - 1]);
          //	cout << i << " " << j << " " << one << endl;
          ans = max(ans, one);
        }
      }
    }
  }
  cout << ans;
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  // freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  // cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}

Fixed submission:
/*input
5
1 - 20 - 13 + 14 - 5
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i, n) for (int i = 1; i <= n; i++)
#define RED(i, n) for (int i = n; i > 0; i--)
#define REPS(i, n) for (int i = 1; (i * i) <= n; i++)
#define REP(i, n) for (int i = 0; i < (int)n; i++)
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define REPD(i, n) for (int i = n - 1; i >= 0; i--)
#define FORD(i, a, b) for (int i = a; i >= b; i--)

#define all(v) v.begin(), v.end()
#define pii pair<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr)                                                             \
  for (auto it = arr.begin(); it != arr.end(); ++it)                           \
    cout << *it << " ";                                                        \
  cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x, y) cout << x << " " << y << endl;
#define debug3(x, y, z) cout << x << " " << y << " " << z << endl;

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;

const int INF = 1e18 + 1;
const int MOD = 1e9 + 7;
const double PI = 3.14159265358979323846264338;

int raise(int a, int n, int m = MOD) {
  if (n == 0)
    return 1;
  if (n == 1)
    return a;
  int x = 1;
  x *= raise(a, n / 2, m);
  x %= m;
  x *= x;
  x %= m;
  if (n % 2)
    x *= a;
  x %= m;
  return x;
}

int floor1(int n, int k) {
  if (n % k == 0 || n >= 0)
    return n / k;
  return (n / k) - 1;
}

int ceil1(int n, int k) { return floor1(n + k - 1, k); }

const int N = 1e5 + 1;
int prefr[N];
int prefa[N];
int n;
int a[N];
int op[N];

void solve() {
  cin >> n;
  op[1] = 1;
  cin >> a[1];
  prefr[1] = prefa[1] = a[1];
  for (int i = 2; i <= n; i++) {
    char o;
    cin >> o;
    op[i] = -1 + 2 * (o == '+');
    cin >> a[i];
    prefr[i] = prefr[i - 1] + a[i] * op[i];
    prefa[i] = prefa[i - 1] + a[i];
  }
  int ans = prefr[n];
  for (int i = 1; i <= n; i++) {
    if (op[i] == -1) {
      for (int j = i + 1; j <= n; j++) {
        if (op[j] == -1) {
          int one = prefr[i - 1] + prefa[n] - prefa[j - 1] -
                    (prefa[j - 1] - prefa[i - 1]);
          //	cout << i << " " << j << " " << one << endl;
          ans = max(ans, one);
          break;
        }
      }
    }
  }
  cout << ans;
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  // freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  // cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}