Problem p00711 (C++) — buggy submission, verdict: Runtime Error

#include <iostream>
#include <string>
#include <vector>
using namespace std;
vector<int> x;
vector<int> y;
vector<int> nextx;
vector<int> nexty;
int w, h;
int count;
bool check(int a, int b) {
  for (int i = 0; i < nextx.size(); i++) {
    if (nextx[i] == a && nexty[i] == b)
      return false;
  }
  return true;
}
int search(int **field) {
  x.clear();
  y.clear();
  for (int i = 0; i < nextx.size(); i++) {
    x.push_back(nextx[i]);
    y.push_back(nexty[i]);
  }
  nextx.clear();
  nexty.clear();
  for (int i = 0; i < x.size(); i++) {
    field[x[i]][y[i]] = 0;
    count++;
  }
  for (int i = 0; i < x.size(); i++) {
    if (field[x[i] - 1][y[i]] == 1 && x[i] - 1 >= 0 && check(x[i] - 1, y[i])) {
      nextx.push_back(x[i] - 1);
      nexty.push_back(y[i]);
    }
    if (x[i] + 1 < h && field[x[i] + 1][y[i]] == 1 && check(x[i] + 1, y[i])) {
      nextx.push_back(x[i] + 1);
      nexty.push_back(y[i]);
    }
    if (field[x[i]][y[i] - 1] == 1 && y[i] - 1 >= 0 && check(x[i], y[i] - 1)) {
      nextx.push_back(x[i]);
      nexty.push_back(y[i] - 1);
    }
    if (field[x[i]][y[i] + 1] == 1 && y[i] + 1 < w && check(x[i], y[i] + 1)) {
      nextx.push_back(x[i]);
      nexty.push_back(y[i] + 1);
    }
  }
  if (nextx.empty()) {
    return -1;
  }
  int *f[h];
  for (int i = 0; i < h; i++)
    f[i] = field[i];
  return search(f);
}
int main() {
  string temp;
  while (cin >> w >> h, w | h != 0) {
    count = 0;
    int field[h][w];
    for (int i = 0; i < h; i++) {
      cin >> temp;
      for (int j = 0; j < w; j++) {
        if (temp[j] == '.')
          field[i][j] = 1;
        if (temp[j] == '#')
          field[i][j] = 0;
        if (temp[j] == '@') {
          field[i][j] = 1;
          nextx.push_back(i);
          nexty.push_back(j);
        }
      }
    }
    int *f[h];
    for (int i = 0; i < h; i++)
      f[i] = field[i];
    search(f);
    cout << count << endl;
  }
}

Error: -11

Fixed submission:

#include <iostream>
#include <string>
#include <vector>
using namespace std;
vector<int> x;
vector<int> y;
vector<int> nextx;
vector<int> nexty;
int w, h;
int count;
bool check(int a, int b) {
  for (int i = 0; i < nextx.size(); i++) {
    if (nextx[i] == a && nexty[i] == b)
      return false;
  }
  return true;
}
int search(int **field) {
  x.clear();
  y.clear();
  for (int i = 0; i < nextx.size(); i++) {
    x.push_back(nextx[i]);
    y.push_back(nexty[i]);
  }
  nextx.clear();
  nexty.clear();
  for (int i = 0; i < x.size(); i++) {
    field[x[i]][y[i]] = 0;
    count++;
  }
  for (int i = 0; i < x.size(); i++) {
    if (field[x[i] - 1][y[i]] == 1 && x[i] - 1 >= 0 && check(x[i] - 1, y[i])) {
      nextx.push_back(x[i] - 1);
      nexty.push_back(y[i]);
    }
    if (field[x[i] + 1][y[i]] == 1 && x[i] + 1 < h && check(x[i] + 1, y[i])) {
      nextx.push_back(x[i] + 1);
      nexty.push_back(y[i]);
    }
    if (field[x[i]][y[i] - 1] == 1 && y[i] - 1 >= 0 && check(x[i], y[i] - 1)) {
      nextx.push_back(x[i]);
      nexty.push_back(y[i] - 1);
    }
    if (field[x[i]][y[i] + 1] == 1 && y[i] + 1 < w && check(x[i], y[i] + 1)) {
      nextx.push_back(x[i]);
      nexty.push_back(y[i] + 1);
    }
  }
  if (nextx.empty()) {
    return -1;
  }
  int *f[h];
  for (int i = 0; i < h; i++)
    f[i] = field[i];
  return search(f);
}
int main() {
  string temp;
  while (cin >> w >> h, w | h != 0) {
    count = 0;
    int field[h][w];
    for (int i = 0; i < h; i++) {
      cin >> temp;
      for (int j = 0; j < w; j++) {
        if (temp[j] == '.')
          field[i][j] = 1;
        if (temp[j] == '#')
          field[i][j] = 0;
        if (temp[j] == '@') {
          field[i][j] = 1;
          nextx.push_back(i);
          nexty.push_back(j);
        }
      }
    }
    int *f[h];
    for (int i = 0; i < h; i++)
      f[i] = field[i];
    search(f);
    cout << count << endl;
  }
}