Problem p02579 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h> // ver2.7.1
#define int long long
#define endl "\\n" // fflush(stdout);
#define ALL(v) (v).begin(), (v).end()
#define Vi vector<int>
#define VVi vector<Vi>
#define VVVi vector<VVi>
#define Vm vector<mint>
#define Vs vector<string>
#define Vd vector<double>
#define Vc vector<char>
#define Pii pair<int, int>
#define Pdd pair<double, double>
#define VPii vector<Pii>
#define Tiii tuple<int, int, int>
#define VTiii vector<Tiii>
#define PQi priority_queue<int>
#define PQir priority_queue<int, vector<int>, greater<int>>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define itos to_string
#define stoi stoll
#define FI first
#define SE second
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define cyes cout << "yes" << endl
#define cno cout << "no" << endl
#define sortr(v) sort(v, greater<>())
#define rep(i, a, b) for (int i = a; i < b; i++)
#define repeq(i, a, b) for (int i = a; i <= b; i++)
#define repreq(i, a, b) for (int i = a; i >= b; i--)
#define dem(a, b) ((a + b - 1) / (b))
#define INF 3000000000000000000 // 3.0*10^18
#define MAX LLONG_MAX
#define PI acos(-1.0L)
// int MOD = 998244353; // case
const int MOD = 1000000007; // 10^9 + 7
const double EPS = 1e-10;

using namespace std;

struct mint {
  int x;
  mint(int x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(int t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

/* debug */
template <typename T> // vector
ostream &operator<<(ostream &os, const vector<T> &V) {
  int N = V.size();
  if (N == 0) {
    os << '.';
    return os;
  }
  rep(i, 0, N - 1) { os << V[i] << ' '; }
  os << V[N - 1];
  return os;
}
template <typename T> // vector vector
ostream &operator<<(ostream &os, const vector<vector<T>> &V) {
  int N = V.size();
  rep(i, 0, N - 1) cout << V[i] << endl;
  cout << V[N - 1];
  return os;
}
template <typename T, typename S> // pair
ostream &operator<<(ostream &os, pair<T, S> const &P) {
  os << P.FI << ' ' << P.SE;
  return os;
}
template <typename T> // set
ostream &operator<<(ostream &os, set<T> &S) {
  auto it = S.begin();
  while (it != S.end()) {
    os << *it;
    if (next(it, 1) != S.end())
      os << ' ';
    it++;
  };
  return os;
}
template <typename T> // deque
ostream &operator<<(ostream &os, deque<T> &q) {
  for (auto it = q.begin(); it < q.end(); it++) {
    os << *it;
    if (it + 1 != q.end())
      os << " ";
  }
  return os;
}

/* useful */
template <typename T> void Vin(vector<T> &v) {
  int n = v.size();
  rep(i, 0, n) cin >> v[i];
}
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int mypow(int x, int n, int m) {
  if (n == 0)
    return 1;
  if (n % 2 == 0)
    return mypow(x * x % m, n / 2, m);
  else
    return x * mypow(x, n - 1, m) % m;
}
int scomb(int n, int r) {
  if (r < 0 || r > n)
    return 0;
  if ((n - r) < r)
    r = n - r; // nCr
  int a = 1;
  for (int i = n; i > n - r; --i) {
    a = a * i;
  }
  for (int i = 1; i < r + 1; ++i) {
    a = a / i;
  }
  return a;
}
Vi vis(Vi &v) {
  Vi S(v.size() + 1);
  rep(i, 1, S.size()) S[i] += v[i - 1] + S[i - 1];
  return S;
}
int digitsum(int n) {
  int ret = 0;
  while (n > 0) {
    ret += n % 10;
    n /= 10;
  }
  return ret;
}
int digit(int k, int i) {
  string s = itos(k);
  return s[s.size() - i] - '0';
} // i桁目の数字
template <typename T> void press(T &v) {
  v.erase(unique(ALL(v)), v.end());
} // 圧縮
Vi zip(Vi b) {
  int Z = b.size(); // 座標圧縮
  Pii p[Z + 10];
  int a = b.size();
  Vi l(a);
  for (int i = 0; i < a; i++)
    p[i] = mp(b[i], i);
  sort(p, p + a);
  int w = 0;
  for (int i = 0; i < a; i++) {
    if (i && p[i].first != p[i - 1].first)
      w++;
    l[p[i].second] = w;
  }
  return l;
}
Vi nibe2V() {
  Vi a(60);
  int q = 1;
  rep(i, 0, 60) {
    a[i] = q;
    q *= 2;
  }
  return a;
}
// Vi nibe = nibe2V(); // 2^n
int modiv(int a, int b) {
  return a * mypow(b, MOD - 2, MOD) % MOD;
} // a÷b(%MOD)
int SMALLER(Vi &a, int x) {
  return lower_bound(a.begin(), a.end(), x) - a.begin();
}
int orSMALLER(Vi &a, int x) {
  return upper_bound(a.begin(), a.end(), x) - a.begin();
}
int BIGGER(Vi &a, int x) { return a.size() - orSMALLER(a, x); }
int orBIGGER(Vi &a, int x) { return a.size() - SMALLER(a, x); }
int COUNT(Vi &a, int x) {
  return upper_bound(ALL(a), x) - lower_bound(ALL(a), x);
}
int maxind(Vi &a) { return max_element(ALL(a)) - a.begin(); }
int minind(Vi &a) { return min_element(ALL(a)) - a.begin(); }
Vi stpowV() {
  Vi a(1000005);
  a[0] = 1;
  repeq(i, 1, 1000004) a[i] = a[i - 1] * i % MOD;
  return a;
}
// Vi stpow = stpowV(); // 階乗配列(%MOD)

/****************************** START ******************************/

int h, w;
bool inside(int i, int j) {
  if (i >= 0 && j >= 0 && i < h && j < w)
    return true;
  else
    return false;
}
Vi dx = {0, 0, 1, -1};
Vi dy = {1, -1, 0, 0};
Vi ex;
Vi ey;

struct edge {
  int to, cost;
};
struct graph {
  int N;
  vector<vector<edge>> G;
  Vi dist;
  graph(int n) { init(n); }
  void init(int n) {
    N = n;
    G.resize(N);
    dist.resize(N);
    rep(i, 0, N) { dist[i] = INF; }
  }
  void add_edge(int s, int t, int cost) {
    edge e;
    e.to = t, e.cost = cost;
    G[s].push_back(e);
  }
  void bfs(int s) {
    rep(i, 0, N) { dist[i] = 0; }
    dist[s] = 1;
    queue<int> q;
    q.push(s);
    while (!q.empty()) {
      int now = q.front();
      q.pop();
      // 終了条件などの処理
      for (auto e : G[now]) {
        if (dist[e.to] == 0) {
          dist[e.to] = dist[now] + 1;
          q.push(e.to);
        }
      }
    }
  }
  void dijkstra(int s) {
    rep(i, 0, N) { dist[i] = INF; }
    dist[s] = 0;
    priority_queue<Pii, vector<Pii>, greater<Pii>> q;
    q.push(mp(0, s));
    while (!q.empty()) {
      int now, nowdist;
      tie(nowdist, now) = q.top();
      q.pop();
      if (dist[now] < nowdist)
        continue;
      for (auto e : G[now]) {
        if (dist[e.to] > dist[now] + e.cost) {
          dist[e.to] = dist[now] + e.cost;
          q.push(mp(dist[e.to], e.to));
        }
      }
    }
  }
  bool bellman_ford(int s) {
    rep(i, 0, N) { dist[i] = INF; }
    dist[s] = 0;
    rep(i, 0, N) {
      rep(j, 0, N) {
        for (auto e : G[j]) {
          if (dist[e.to] > dist[j] + e.cost) {
            dist[e.to] = dist[j] + e.cost;
            if (i == N - 1) {
              // 閉路発見！
              return false;
            }
          }
        }
      }
    }
    return true;
  }
};

signed main() {
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);
  cin >> h >> w;
  Pii S, G;
  int qw, er;
  cin >> qw >> er;
  qw--, er--;
  S = mp(qw, er);
  cin >> qw >> er;
  qw--, er--;
  G = mp(qw, er);
  Vs mapp(h);
  Vin(mapp);

  repeq(i, -2, 2) repeq(j, -2, 2) {
    if (i == 0 && j == 0)
      continue;
    if (i == -1 && j == 0)
      continue;
    if (i == 1 && j == 0)
      continue;
    if (i == 0 && j == -1)
      continue;
    if (i == 0 && j == 1)
      continue;
    ex.pb(i);
    ey.pb(j);
  }
  int ct = 0;
  graph gr(h * w);
  VVi are(h, Vi(w));
  rep(i, 0, h) {
    rep(j, 0, w) {
      are[i][j] = ct;
      ct++;
    }
  }
  rep(i, 0, h) rep(j, 0, w) {
    rep(k, 0, 4) {
      if (inside(i + dx[k], j + dy[k]) && mapp[i + dx[k]][j + dy[k]] == '.') {
        gr.add_edge(are[i][j], are[i + dx[k]][j + dy[k]], 0);
      }
    }
    rep(k, 0, 20) {
      if (inside(i + ex[k], j + ey[k]) && mapp[i + ex[k]][j + ey[k]] == '.') {
        gr.add_edge(are[i][j], are[i + ex[k]][j + ey[k]], 1);
      }
    }
  }
  gr.dijkstra(are[S.FI][S.SE]);
  int ans = gr.dist[are[G.FI][G.SE]];
  if (ans >= INF / 2)
    ans = -1;
  cout << ans << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h> // ver2.7.1
#define int long long
#define endl "\\n" // fflush(stdout);
#define ALL(v) (v).begin(), (v).end()
#define Vi vector<int>
#define VVi vector<Vi>
#define VVVi vector<VVi>
#define Vm vector<mint>
#define Vs vector<string>
#define Vd vector<double>
#define Vc vector<char>
#define Pii pair<int, int>
#define Pdd pair<double, double>
#define VPii vector<Pii>
#define Tiii tuple<int, int, int>
#define VTiii vector<Tiii>
#define PQi priority_queue<int>
#define PQir priority_queue<int, vector<int>, greater<int>>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define itos to_string
#define stoi stoll
#define FI first
#define SE second
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define cyes cout << "yes" << endl
#define cno cout << "no" << endl
#define sortr(v) sort(v, greater<>())
#define rep(i, a, b) for (int i = a; i < b; i++)
#define repeq(i, a, b) for (int i = a; i <= b; i++)
#define repreq(i, a, b) for (int i = a; i >= b; i--)
#define dem(a, b) ((a + b - 1) / (b))
#define INF 3000000000000000000 // 3.0*10^18
#define MAX LLONG_MAX
#define PI acos(-1.0L)
// int MOD = 998244353; // case
const int MOD = 1000000007; // 10^9 + 7
const double EPS = 1e-10;

using namespace std;

struct mint {
  int x;
  mint(int x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(int t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

/* debug */
template <typename T> // vector
ostream &operator<<(ostream &os, const vector<T> &V) {
  int N = V.size();
  if (N == 0) {
    os << '.';
    return os;
  }
  rep(i, 0, N - 1) { os << V[i] << ' '; }
  os << V[N - 1];
  return os;
}
template <typename T> // vector vector
ostream &operator<<(ostream &os, const vector<vector<T>> &V) {
  int N = V.size();
  rep(i, 0, N - 1) cout << V[i] << endl;
  cout << V[N - 1];
  return os;
}
template <typename T, typename S> // pair
ostream &operator<<(ostream &os, pair<T, S> const &P) {
  os << P.FI << ' ' << P.SE;
  return os;
}
template <typename T> // set
ostream &operator<<(ostream &os, set<T> &S) {
  auto it = S.begin();
  while (it != S.end()) {
    os << *it;
    if (next(it, 1) != S.end())
      os << ' ';
    it++;
  };
  return os;
}
template <typename T> // deque
ostream &operator<<(ostream &os, deque<T> &q) {
  for (auto it = q.begin(); it < q.end(); it++) {
    os << *it;
    if (it + 1 != q.end())
      os << " ";
  }
  return os;
}

/* useful */
template <typename T> void Vin(vector<T> &v) {
  int n = v.size();
  rep(i, 0, n) cin >> v[i];
}
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int mypow(int x, int n, int m) {
  if (n == 0)
    return 1;
  if (n % 2 == 0)
    return mypow(x * x % m, n / 2, m);
  else
    return x * mypow(x, n - 1, m) % m;
}
int scomb(int n, int r) {
  if (r < 0 || r > n)
    return 0;
  if ((n - r) < r)
    r = n - r; // nCr
  int a = 1;
  for (int i = n; i > n - r; --i) {
    a = a * i;
  }
  for (int i = 1; i < r + 1; ++i) {
    a = a / i;
  }
  return a;
}
Vi vis(Vi &v) {
  Vi S(v.size() + 1);
  rep(i, 1, S.size()) S[i] += v[i - 1] + S[i - 1];
  return S;
}
int digitsum(int n) {
  int ret = 0;
  while (n > 0) {
    ret += n % 10;
    n /= 10;
  }
  return ret;
}
int digit(int k, int i) {
  string s = itos(k);
  return s[s.size() - i] - '0';
} // i桁目の数字
template <typename T> void press(T &v) {
  v.erase(unique(ALL(v)), v.end());
} // 圧縮
Vi zip(Vi b) {
  int Z = b.size(); // 座標圧縮
  Pii p[Z + 10];
  int a = b.size();
  Vi l(a);
  for (int i = 0; i < a; i++)
    p[i] = mp(b[i], i);
  sort(p, p + a);
  int w = 0;
  for (int i = 0; i < a; i++) {
    if (i && p[i].first != p[i - 1].first)
      w++;
    l[p[i].second] = w;
  }
  return l;
}
Vi nibe2V() {
  Vi a(60);
  int q = 1;
  rep(i, 0, 60) {
    a[i] = q;
    q *= 2;
  }
  return a;
}
// Vi nibe = nibe2V(); // 2^n
int modiv(int a, int b) {
  return a * mypow(b, MOD - 2, MOD) % MOD;
} // a÷b(%MOD)
int SMALLER(Vi &a, int x) {
  return lower_bound(a.begin(), a.end(), x) - a.begin();
}
int orSMALLER(Vi &a, int x) {
  return upper_bound(a.begin(), a.end(), x) - a.begin();
}
int BIGGER(Vi &a, int x) { return a.size() - orSMALLER(a, x); }
int orBIGGER(Vi &a, int x) { return a.size() - SMALLER(a, x); }
int COUNT(Vi &a, int x) {
  return upper_bound(ALL(a), x) - lower_bound(ALL(a), x);
}
int maxind(Vi &a) { return max_element(ALL(a)) - a.begin(); }
int minind(Vi &a) { return min_element(ALL(a)) - a.begin(); }
Vi stpowV() {
  Vi a(1000005);
  a[0] = 1;
  repeq(i, 1, 1000004) a[i] = a[i - 1] * i % MOD;
  return a;
}
// Vi stpow = stpowV(); // 階乗配列(%MOD)

/****************************** START ******************************/

int h, w;
bool inside(int i, int j) {
  if (i >= 0 && j >= 0 && i < h && j < w)
    return true;
  else
    return false;
}
Vi dx = {0, 0, 1, -1};
Vi dy = {1, -1, 0, 0};
Vi ex;
Vi ey;

signed main() {
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);
  cin >> h >> w;
  Pii S, G;
  int qw, er;
  cin >> qw >> er;
  qw--, er--;
  S = mp(qw, er);
  cin >> qw >> er;
  qw--, er--;
  G = mp(qw, er);
  Vs mapp(h);
  Vin(mapp);

  repeq(i, -2, 2) repeq(j, -2, 2) {
    if (i == 0 && j == 0)
      continue;
    if (i == -1 && j == 0)
      continue;
    if (i == 1 && j == 0)
      continue;
    if (i == 0 && j == -1)
      continue;
    if (i == 0 && j == 1)
      continue;
    ex.pb(i);
    ey.pb(j);
  }
  // cout << ex << endl;
  // cout << ey << endl;
  // cout << ey.size() << endl;

  VVi ans(h, Vi(w, INF));
  queue<Pii> ne;
  ne.push(S);
  ans[S.FI][S.SE] = 0;
  char c = '.';

  while (!ne.empty()) {
    int x, y;
    tie(x, y) = ne.front();
    ne.pop();
    int pt = ans[x][y];
    rep(i, 0, 4) {
      if (inside(dx[i] + x, dy[i] + y) && ans[dx[i] + x][dy[i] + y] > pt &&
          mapp[dx[i] + x][dy[i] + y] == c) {
        ne.push(mp(dx[i] + x, dy[i] + y));
        ans[dx[i] + x][dy[i] + y] = pt;
      }
    }
    rep(i, 0, 20) {
      if (inside(ex[i] + x, ey[i] + y) && ans[ex[i] + x][ey[i] + y] > pt &&
          mapp[ex[i] + x][ey[i] + y] == c) {
        ne.push(mp(ex[i] + x, ey[i] + y));
        ans[ex[i] + x][ey[i] + y] = pt + 1;
      }
    }
  }
  // cout << ans << endl;
  int out = ans[G.FI][G.SE];
  if (out >= INF / 2)
    out = -1;
  cout << out << endl;
  return 0;
}