Problem p02704 (C++) — buggy submission, verdict: Runtime Error

#include <iostream>
#include <vector>
using namespace std;
typedef unsigned long long ll;

ll ans[503][503];
int n;
ll s[503], t[503], u[503], v[503];

bool ok() {
  for (int i = 0; i < n; i++) {
    if (s[i] == 0) {
      ll r = -1;
      for (int j = 0; j < n; j++)
        r &= ans[i][j];
      if (r != u[i])
        return false;
    } else {
      ll r = 0;
      for (int j = 0; j < n; j++)
        r |= ans[i][j];
      if (r != u[i])
        return false;
    }
  }
  for (int j = 0; j < n; j++) {
    if (t[j] == 0) {
      ll r = -1;
      for (int i = 0; i < n; i++)
        r &= ans[i][j];
      if (r != v[j])
        return false;
    } else {
      ll r = 0;
      for (int i = 0; i < n; i++)
        r |= ans[i][j];
      if (r != v[j])
        return false;
    }
  }
  return true;
}

void show() {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++)
      cout << ans[i][j] << " ";
    cout << endl;
  }
}

int main() {
  cin >> n;
  vector<int> x, y;
  for (int i = 0; i < n; i++) {
    cin >> s[i];
    if (s[i] == 0)
      x.push_back(i);
  }
  for (int i = 0; i < n; i++) {
    cin >> t[i];
    if (t[i] == 0)
      y.push_back(i);
  }
  for (int i = 0; i < n; i++)
    cin >> u[i];
  for (int i = 0; i < n; i++)
    cin >> v[i];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (!(s[i] | t[j]))
        ans[i][j] = u[i] | v[j];
      if (s[i] & t[j])
        ans[i][j] = u[i] & v[j];
    }
  }
  int a = x.size(), b = y.size();
  int p = -1;
  if (a == 1) {
    for (int j = 0; j < n; j++) {
      if (t[j] == 0) {
        continue;
      }
      ll r = 0;
      for (int i = 0; i < n; i++) {
        r |= ans[i][j];
      }
      ans[x[0]][j] = (v[j] & (~r)) | u[x[0]];
      p = x[0];
    }
  }
  if (b == 1) {
    for (int i = 0; i < n; i++) {
      if (s[i] == 0) {
        continue;
      }
      ll r = 0;
      for (int j = 0; j < n; j++) {
        if (j == y[0])
          continue;
        r |= ans[i][j];
      }
      if ((r | u[i]) != u[i]) {
        cout << -1 << endl;
        return 0;
      }
      ans[i][y[0]] = (u[i] & (~r)) | v[y[0]];
      p = y[0];
    }
  }
  if (a == n - 1) {
    for (int j = 0; j < n; j++) {
      if (t[j] == 1)
        continue;
      ll r = -1;
      for (int i = 0; i < n; i++) {
        if (s[i] == 0)
          r &= ans[i][j];
        else
          p = i;
      }
      ans[p][j] = (u[p] & (~r)) | v[j];
    }
  }
  if (b == n - 1) {
    for (int i = 0; i < n; i++) {
      if (s[i] == 1)
        continue;
      ll r = -1;
      for (int j = 0; j < n; j++) {
        if (t[j] == 0)
          r &= ans[i][j];
        else
          p = j;
      }
      ans[i][p] = (v[p] & (~r)) | u[i];
    }
  } else {
    int k1 = 0, k2 = 0;
    for (int i = 0; i < n; i++) {
      if (i == p)
        continue;
      int k;
      if (s[i] == 0) {
        k = k1;
        k1 = 1 - k1;
      } else {
        k = k2;
        k2 = 1 - k2;
      }
      for (int j = 0; j < n; j++) {
        if (s[i] != t[j]) {
          if (k)
            ans[i][j] = v[j];
          else
            ans[i][j] = u[i];
          k = 1 - k;
        }
      }
    }
  }
  if (ok()) {
    show();
  } else {
    cout << -1 << endl;
  }
}


Error: WA

Fixed submission:

#include <iostream>
#include <vector>
using namespace std;
typedef unsigned long long ll;

ll ans[503][503];
int n;
ll s[503], t[503], u[503], v[503];

bool ok() {
  for (int i = 0; i < n; i++) {
    if (s[i] == 0) {
      ll r = -1;
      for (int j = 0; j < n; j++)
        r &= ans[i][j];
      if (r != u[i])
        return false;
    } else {
      ll r = 0;
      for (int j = 0; j < n; j++)
        r |= ans[i][j];
      if (r != u[i])
        return false;
    }
  }
  for (int j = 0; j < n; j++) {
    if (t[j] == 0) {
      ll r = -1;
      for (int i = 0; i < n; i++)
        r &= ans[i][j];
      if (r != v[j])
        return false;
    } else {
      ll r = 0;
      for (int i = 0; i < n; i++)
        r |= ans[i][j];
      if (r != v[j])
        return false;
    }
  }
  return true;
}

void show() {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++)
      cout << ans[i][j] << " ";
    cout << endl;
  }
}

int main() {
  cin >> n;
  for (int i = 0; i < n; i++)
    cin >> s[i];
  for (int i = 0; i < n; i++)
    cin >> t[i];
  for (int i = 0; i < n; i++)
    cin >> u[i];
  for (int i = 0; i < n; i++)
    cin >> v[i];
  vector<int> x, y;
  for (int i = 0; i < n; i++) {
    if (s[i] == 0) {
      for (int j = 0; j < n; j++)
        ans[i][j] |= u[i];
      x.push_back(i);
    }
  }
  for (int j = 0; j < n; j++) {
    if (t[j] == 0) {
      for (int i = 0; i < n; i++)
        ans[i][j] |= v[j];
      y.push_back(j);
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (s[i] & t[j])
        ans[i][j] = u[i] & v[j];
    }
  }
  ll lx[502], ly[502];
  for (int i = 0; i < n; i++) {
    if (s[i] == 0)
      continue;
    ll r = 0;
    for (int j = 0; j < n; j++) {
      r |= ans[i][j];
    }
    if ((r | u[i]) != u[i]) {
      cout << -1 << endl;
      return 0;
    }
    lx[i] = u[i] & (~r);
  }
  for (int j = 0; j < n; j++) {
    if (t[j] == 0)
      continue;
    ll r = 0;
    for (int i = 0; i < n; i++) {
      r |= ans[i][j];
    }
    if ((r | v[j]) != v[j]) {
      cout << -1 << endl;
      return 0;
    }
    ly[j] = v[j] & (~r);
  }
  int a = x.size(), b = y.size();
  if (a == 1) {
    for (int j = 0; j < n; j++) {
      if (t[j] == 0)
        continue;
      ans[x[0]][j] |= ly[j];
    }
    if (ok()) {
      show();
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  if (b == 1) {
    for (int i = 0; i < n; i++) {
      if (s[i] == 0)
        continue;
      ans[i][y[0]] |= lx[i];
    }
    if (ok()) {
      show();
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  if (a == n - 1) {
    for (int j = 0; j < n; j++) {
      if (t[j] == 1)
        continue;
      ll r = -1;
      int p;
      for (int i = 0; i < n; i++) {
        if (s[i] == 0)
          r &= ans[i][j];
        else
          p = i;
      }
      ans[p][j] |= u[p] & (~r);
    }
    if (ok()) {
      show();
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  if (b == n - 1) {
    for (int i = 0; i < n; i++) {
      if (s[i] == 1)
        continue;
      ll r = -1;
      int p;
      for (int j = 0; j < n; j++) {
        if (t[j] == 0)
          r &= ans[i][j];
        else
          p = j;
      }
      ans[i][p] = v[p] & (~r);
    }
    if (ok()) {
      show();
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  for (int i = 0; i < n; i++) {
    if (s[i] == 0)
      continue;
    ans[i][y[i % b]] |= u[i];
  }
  for (int j = 0; j < n; j++) {
    if (t[j] == 0)
      continue;
    ans[x[j % a]][j] |= v[j];
  }
  if (ok()) {
    show();
  } else {
    cout << -1 << endl;
  }
}