/bin/run.sh: line 4: 18 Segmentation fault (core dumped) ./exe

Question

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

int solve(int A, vector<int> &B) {
  vector<int> pre(A);
  vector<int> suff(A);
  vector<int> p;
  vector<int> s;
  int sum = 0;
  int ans = 0;

  for (int i = 0; i < A; i++) {
    sum = sum + B[i];
  }
  if (sum % 3 != 0)
    return 0;
  sum = sum / 3;

  for (int i = 0; i < A; i++) {
    if (i == 0) {
      pre[i] = B[i];
      if (pre[i] == sum) {
        p.push_back(i);
      }
      continue;
    }
    pre[i] = B[i] + pre[i - 1];
    if (pre[i] == sum) {
      p.push_back(i);
    }
  }

  for (int i = A - 1; i >= 0; i--) {
    if (i == A - 1) {
      suff[A - 1] = B[A - 1];
      if (suff[i] == sum) {
        s.push_back(i);
      }
      continue;
    }
    suff[i] = B[i] + pre[i + 1];
    if (suff[i] == sum) {
      s.push_back(i);
    }
  }
  for (int i = 0; i < p.size(); i++) {
    for (int j = s.size(); j >= 0; j++) {
      if (s[j] > p[i] + 1) {
        ans++;
      }
    }
  }
  return ans;
}

int main() {
  int A = 5;
  vector<int> B = {1, 2, 3, 0, 3};
  cout << solve(5, B);
  return 0;
}

The code keeps getting dumped at pre[i]=B[i]. The code is very simple for counting the number of ways to split all the elements of the array into 3 contiguous parts so that the sum of elements in each part is the same.

I just made a prefix and suffix sum array.