Problem p02579 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using VVI = vector<VI>;
using VVL = vector<VL>;
using PII = std::pair<int, int>;
using VPII = std::vector<std::pair<int, int>>;
using PLL = std::pair<ll, ll>;
using VPLL = std::vector<std::pair<ll, ll>>;
using TI3 = std::tuple<int, int, int>;
using TI4 = std::tuple<int, int, int, int>;
using TL3 = std::tuple<ll, ll, ll>;
using TL4 = std::tuple<ll, ll, ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define rep3(i, s, n, d) for (int i = (s); i < (int)(n); i += (d))
#define allpt(v) (v).begin(), (v).end()
#define allpt_c(v) (v).cbegin(), (v).cend()
#define allpt_r(v) (v).rbegin(), (v).rend()
#define allpt_cr(v) (v).crbegin(), (v).crend()

const int mod1 = 1e9 + 7, mod2 = 998244353, mod3 = 1e9 + 9;
const int mod = mod1;
const ll inf = 1e18;

const string wsp = " ";
const string tb = "\\t";
const string rt = "\\n";
const string alphabets = "abcdefghijklmnopqrstuvwxyz";

template <typename T> void show1dvec(const vector<T> &v) {
  if (v.size() == 0)
    return;
  int n = v.size() - 1;
  rep(i, n) cout << v[i] << wsp;
  cout << v[n] << rt;

  return;
}

template <typename T> void show2dvec(const vector<vector<T>> &v) {
  int n = v.size();
  rep(i, n) show1dvec(v[i]);
}

template <typename T, typename S> void show1dpair(const vector<pair<T, S>> &v) {
  int n = v.size();
  rep(i, n) cout << v[i].first << wsp << v[i].second << rt;
  return;
}

template <typename T, typename S>
void pairzip(const vector<pair<T, S>> &v, vector<T> &t, vector<T> &s) {
  int n = v.size();
  rep(i, n) {
    t.push_back(v[i].first);
    s.push_back(v[i].second);
  }
  return;
}

template <typename T> void maxvec(vector<T> &v) {
  T s = v[0];
  int n = v.size();
  rep(i, n - 1) {
    if (s > v[i + 1]) {
      v[i + 1] = s;
    }
    s = v[i + 1];
  }
}

template <typename T, typename S> bool myfind(T t, S s) {
  return find(t.cbegin(), t.cend(), s) != t.cend();
}

bool check(int y, int x, int h, int w) {
  return 0 <= y && y < h && 0 <= x && x < w;
}

bool iskadomatsu(int a, int b, int c) {
  return (a != b && b != c && c != a) && ((a > b && b < c) || (a < b && b > c));
}

double euc_dist(PII a, PII b) {
  return sqrt(pow(a.first - b.first, 2) + pow(a.second - b.second, 2));
}

VS split(string s, char c) {
  VS ret;
  string part;
  s += c;
  rep(i, s.length()) {
    if (s[i] == c) {
      ret.emplace_back(part);
      part = "";
    } else if (s[i] != c) {
      part += s[i];
    }
  }
  return ret;
}

template <typename T, typename S, typename R>
ll pow_mod(T p, S q, R mod = 1ll) {
  ll ret = 1, r = p;
  while (q) {
    if (q % 2)
      ret *= r, ret %= mod;
    r = (r * r) % mod, q /= 2;
  }
  return ret % mod;
}

template <typename T, typename S> ll pow_no_mod(T p, S q) {
  ll ret = 1, r = p;
  while (q) {
    if (q % 2)
      ret *= r;
    r = (r * r), q /= 2;
  }
  return ret;
}

void make_frac_tables(VL &frac_list, VL &frac_inv_list) {
  rep(i, frac_list.size() - 1) {
    frac_list[i + 1] *= frac_list[i] * (i + 1);
    frac_list[i + 1] %= mod;
    frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod);
    frac_inv_list[i + 1] %= mod;
  }
}

pair<VL, VL> make_frac_tables(int n) {
  VL frac_list(n + 1, 1), frac_inv_list(n + 1, 1);
  rep(i, n) {
    frac_list[i + 1] *= frac_list[i] * (i + 1);
    frac_list[i + 1] %= mod;
    frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod);
    frac_inv_list[i + 1] %= mod;
  }
  return make_pair(frac_list, frac_inv_list);
}

ll comb(int a, int b, const VL &frac_list, const VL &frac_inv_list) {
  if (a < b)
    return 0;
  if (b < 0)
    return 0;
  ll ret = frac_list[a];
  ret *= frac_inv_list[b];
  ret %= mod;
  ret *= frac_inv_list[a - b];
  ret %= mod;
  return ret;
}

void djkstra(int n, int s, int t, const vector<set<int>> &connect) {
  const int intm = 1e9;
  vector<int> shortest(n, intm);
  shortest[s] = 0;
  vector<int> search = {s};
  vector<int> new_search;
  while (!search.empty()) {
    for (auto i : search) {
      for (auto j : connect[i]) {
        if (shortest[j] > 1 + shortest[i]) {
          shortest[j] = 1 + shortest[i];
          new_search.emplace_back(j);
        }
      }
    }
    search.clear();
    search = new_search;
    new_search.clear();
    // show1dvec(search);
    // show1dvec(shortest);
  }
  if (shortest[t] == intm)
    shortest[t] = -1;
  printf("%d\\n", shortest[t]);
}

int h, w;

void dfs(VS &field, VVI &field2, int y, int x, int n) {
  field2[y][x] = n;
  if (check(y + 1, x, h, w) && field[y + 1][x] == '.' &&
      field2[y + 1][x] == -1) {
    field2[y + 1][x] = n;
    dfs(field, field2, y + 1, x, n);
  }
  if (check(y - 1, x, h, w) && field[y - 1][x] == '.' &&
      field2[y - 1][x] == -1) {
    field2[y - 1][x] = n;
    dfs(field, field2, y - 1, x, n);
  }
  if (check(y, x + 1, h, w) && field[y][x + 1] == '.' &&
      field2[y][x + 1] == -1) {
    field2[y][x + 1] = n;
    dfs(field, field2, y, x + 1, n);
  }
  if (check(y, x - 1, h, w) && field[y][x - 1] == '.' &&
      field2[y][x - 1] == -1) {
    field2[y][x - 1] = n;
    dfs(field, field2, y, x - 1, n);
  }
}

int main() {
  // cin.tie(0);
  // ios::sync_with_stdio(false);

#ifdef DEBUG
  cout << "DEBUG MODE" << endl;
  ifstream in("input.txt"); // for debug
  cin.rdbuf(in.rdbuf());    // for debug
#endif

  int cy, cx, dy, dx;
  cin >> h >> w >> cy >> cx >> dy >> dx;

  VS field(h);
  VVI field2(h, VI(w, -1));
  rep(i, h) cin >> field[i];

  // rep(i, h) cout << field[i] << rt;
  int c = 0;
  rep(i, h) rep(j, w) if (field[i][j] == '.' && field2[i][j] == -1) {
    dfs(field, field2, i, j, c);
    c++;
  }

  vector<set<int>> connect(c);

  rep(i, h) rep(j, w) rep2(di, -2, 3) rep2(
      dj, -2, 3) if (check(i + di, j + dj, h,
                           w)) if (field2[i][j] != -1 &&
                                   field2[i + di][j + dj] != -1 &&
                                   field2[i][j] != field2[i + di][j + dj]) {
    int a = field2[i][j];
    int b = field2[i + di][j + dj];
    // cout << i << wsp << j << tb << i + di << wsp << j + dj << tb << a <<
    // wsp
    //      << b << rt;
    connect[a].insert(b);
    connect[b].insert(a);
  }

  djkstra(c, field2[cy - 1][cx - 1], field2[dy - 1][dx - 1], connect);

  // show2dvec(field2);
  return 0;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using VVI = vector<VI>;
using VVL = vector<VL>;
using PII = std::pair<int, int>;
using VPII = std::vector<std::pair<int, int>>;
using PLL = std::pair<ll, ll>;
using VPLL = std::vector<std::pair<ll, ll>>;
using TI3 = std::tuple<int, int, int>;
using TI4 = std::tuple<int, int, int, int>;
using TL3 = std::tuple<ll, ll, ll>;
using TL4 = std::tuple<ll, ll, ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define rep3(i, s, n, d) for (int i = (s); i < (int)(n); i += (d))
#define allpt(v) (v).begin(), (v).end()
#define allpt_c(v) (v).cbegin(), (v).cend()
#define allpt_r(v) (v).rbegin(), (v).rend()
#define allpt_cr(v) (v).crbegin(), (v).crend()

const int mod1 = 1e9 + 7, mod2 = 998244353, mod3 = 1e9 + 9;
const int mod = mod1;
const ll inf = 1e18;

const string wsp = " ";
const string tb = "\\t";
const string rt = "\\n";
const string alphabets = "abcdefghijklmnopqrstuvwxyz";

template <typename T> void show1dvec(const vector<T> &v) {
  if (v.size() == 0)
    return;
  int n = v.size() - 1;
  rep(i, n) cout << v[i] << wsp;
  cout << v[n] << rt;

  return;
}

template <typename T> void show2dvec(const vector<vector<T>> &v) {
  int n = v.size();
  rep(i, n) show1dvec(v[i]);
}

template <typename T, typename S> void show1dpair(const vector<pair<T, S>> &v) {
  int n = v.size();
  rep(i, n) cout << v[i].first << wsp << v[i].second << rt;
  return;
}

template <typename T, typename S>
void pairzip(const vector<pair<T, S>> &v, vector<T> &t, vector<T> &s) {
  int n = v.size();
  rep(i, n) {
    t.push_back(v[i].first);
    s.push_back(v[i].second);
  }
  return;
}

template <typename T> void maxvec(vector<T> &v) {
  T s = v[0];
  int n = v.size();
  rep(i, n - 1) {
    if (s > v[i + 1]) {
      v[i + 1] = s;
    }
    s = v[i + 1];
  }
}

template <typename T, typename S> bool myfind(T t, S s) {
  return find(t.cbegin(), t.cend(), s) != t.cend();
}

bool check(int y, int x, int h, int w) {
  return 0 <= y && y < h && 0 <= x && x < w;
}

bool iskadomatsu(int a, int b, int c) {
  return (a != b && b != c && c != a) && ((a > b && b < c) || (a < b && b > c));
}

double euc_dist(PII a, PII b) {
  return sqrt(pow(a.first - b.first, 2) + pow(a.second - b.second, 2));
}

VS split(string s, char c) {
  VS ret;
  string part;
  s += c;
  rep(i, s.length()) {
    if (s[i] == c) {
      ret.emplace_back(part);
      part = "";
    } else if (s[i] != c) {
      part += s[i];
    }
  }
  return ret;
}

template <typename T, typename S, typename R>
ll pow_mod(T p, S q, R mod = 1ll) {
  ll ret = 1, r = p;
  while (q) {
    if (q % 2)
      ret *= r, ret %= mod;
    r = (r * r) % mod, q /= 2;
  }
  return ret % mod;
}

template <typename T, typename S> ll pow_no_mod(T p, S q) {
  ll ret = 1, r = p;
  while (q) {
    if (q % 2)
      ret *= r;
    r = (r * r), q /= 2;
  }
  return ret;
}

void make_frac_tables(VL &frac_list, VL &frac_inv_list) {
  rep(i, frac_list.size() - 1) {
    frac_list[i + 1] *= frac_list[i] * (i + 1);
    frac_list[i + 1] %= mod;
    frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod);
    frac_inv_list[i + 1] %= mod;
  }
}

pair<VL, VL> make_frac_tables(int n) {
  VL frac_list(n + 1, 1), frac_inv_list(n + 1, 1);
  rep(i, n) {
    frac_list[i + 1] *= frac_list[i] * (i + 1);
    frac_list[i + 1] %= mod;
    frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod);
    frac_inv_list[i + 1] %= mod;
  }
  return make_pair(frac_list, frac_inv_list);
}

ll comb(int a, int b, const VL &frac_list, const VL &frac_inv_list) {
  if (a < b)
    return 0;
  if (b < 0)
    return 0;
  ll ret = frac_list[a];
  ret *= frac_inv_list[b];
  ret %= mod;
  ret *= frac_inv_list[a - b];
  ret %= mod;
  return ret;
}

void djkstra(int n, int s, int t, const vector<set<int>> &connect) {
  const int intm = 1e8;
  vector<int> shortest(100000, intm);
  shortest[s] = 0;
  vector<int> search = {0};
  vector<int> new_search;
  while (!search.empty()) {
    for (auto i : search) {
      for (auto j : connect[i]) {
        if (shortest[j] > 1 + shortest[i]) {
          shortest[j] = 1 + shortest[i];
          new_search.emplace_back(j);
        }
      }
    }
    search.clear();
    search = new_search;
    new_search.clear();
    // show1dvec(search);
    // show1dvec(shortest);
  }
  if (shortest[t] == intm)
    shortest[t] = -1;
  printf("%d\\n", shortest[t]);
}

int h, w;

void dfs(VS &field, VVI &field2, int y, int x, int n) {
  field2[y][x] = n;
  if (check(y + 1, x, h, w) && field[y + 1][x] == '.' &&
      field2[y + 1][x] == -1) {
    field2[y + 1][x] = n;
    dfs(field, field2, y + 1, x, n);
  }
  if (check(y - 1, x, h, w) && field[y - 1][x] == '.' &&
      field2[y - 1][x] == -1) {
    field2[y - 1][x] = n;
    dfs(field, field2, y - 1, x, n);
  }
  if (check(y, x + 1, h, w) && field[y][x + 1] == '.' &&
      field2[y][x + 1] == -1) {
    field2[y][x + 1] = n;
    dfs(field, field2, y, x + 1, n);
  }
  if (check(y, x - 1, h, w) && field[y][x - 1] == '.' &&
      field2[y][x - 1] == -1) {
    field2[y][x - 1] = n;
    dfs(field, field2, y, x - 1, n);
  }
}

int main() {
  // cin.tie(0);
  // ios::sync_with_stdio(false);

#ifdef DEBUG
  cout << "DEBUG MODE" << endl;
  ifstream in("input.txt"); // for debug
  cin.rdbuf(in.rdbuf());    // for debug
#endif

  int cy, cx, dy, dx;
  cin >> h >> w >> cy >> cx >> dy >> dx;

  VS field(h);
  VVI field2(h, VI(w, -1));
  rep(i, h) cin >> field[i];

  // rep(i, h) cout << field[i] << rt;
  int c = 0;
  rep(i, h) rep(j, w) if (field[i][j] == '.' && field2[i][j] == -1) {
    dfs(field, field2, i, j, c);
    c++;
  }

  vector<set<int>> connect(c);

  rep(i, h) rep(j, w) rep2(di, -2, 3) rep2(
      dj, -2, 3) if (check(i + di, j + dj, h,
                           w)) if (field2[i][j] != -1 &&
                                   field2[i + di][j + dj] != -1 &&
                                   field2[i][j] != field2[i + di][j + dj]) {
    int a = field2[i][j];
    int b = field2[i + di][j + dj];
    // cout << i << wsp << j << tb << i + di << wsp << j + dj << tb << a <<
    // wsp
    //      << b << rt;
    connect[a].insert(b);
    connect[b].insert(a);
  }

  djkstra(c, field2[cy - 1][cx - 1], field2[dy - 1][dx - 1], connect);

  return 0;
}