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

#include <algorithm>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using vl = vector<ll>;
using vll = vector<vl>;
using vlll = vector<vll>;
using vpll = vector<pll>;
using vs = vector<string>;
using tll = tuple<ll, ll, ll>;
using vtll = vector<tll>;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const ld PI = 3.1415926535897932;
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define co(i) cout << i << endl;
#define co2(i, j) cout << i << " " << j << endl;
#define co3(i) cout << i << " ";
#define po(i) cout << i.first << " " << i.second << endl;
void in() {}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail> void debug_out(Head h, Tail... t) {
  cerr << " " << h;
  if (sizeof...(t) > 0)
    cerr << " :";
  debug_out(t...);
}
template <typename T> ostream &operator<<(ostream &os, vector<T> vec) {
  for (size_t i = 0; i < vec.size(); i++)
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
ll ctoi(char c) {
  switch (c) {
  case '0':
    return 0;
  case '1':
    return 1;
  case '2':
    return 2;
  case '3':
    return 3;
  case '4':
    return 4;
  case '5':
    return 5;
  case '6':
    return 6;
  case '7':
    return 7;
  case '8':
    return 8;
  case '9':
    return 9;
  default:
    return 0;
  }
}
bool pairCompare(const pll firstElof, pll secondElof) {
  return firstElof.second < secondElof.second;
}
//**Snippetリスト**//
// rep, vin, all, iteLoop, bitSearch, bitList, nod, LIS, digitDP, treeDP,
// Rerooting// gcdlcm, isPrime, eratos, primeFactorize, Npow, combination,
// divisor, modinv, doubling// dfs, bfs, dijkstra, WarshallFloyd, BellmanFord,
// UnionFind, Kruskal, RMQ, LCA, FordFulkerson//
ll i, j, k, l;
ll N, M, K, H, W, L, X, Y, Z, R, Q, T;
ll MOD = 1000000007, INF = 1LL << 60, ans = 0, z = 0, o = 1;
vll flag, D;
vector<vpll> path;
vs S;
void bfs(ll x, ll y) {
  priority_queue<tll> Q;
  Q.push(mt(0, x, y));
  D[x][y] = 0;
  ll q = -1;
  tll u;
  while (!Q.empty()) {
    u = Q.top();
    ll x = get<1>(u);
    ll y = get<2>(u);
    Q.pop();
    ll nx = x, ny = y;
    nx = x - 1;
    ny = y;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x + 1;
    ny = y;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    // ここから魔法
    nx = x - 1;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x - 1;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x + 1;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x + 1;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mt(D[nx][ny] * q, nx, ny));
      }
    }
    nx = x - 2;
    for (ll i = y - 2; i <= y + 2; i++) {
      ny = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mt(D[nx][ny] * q, nx, ny));
        }
      }
    }
    nx = x + 2;
    for (ll i = y - 2; i <= y + 2; i++) {
      ny = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mt(D[nx][ny] * q, nx, ny));
        }
      }
    }
    ny = y - 2;
    for (ll i = x - 1; i <= x + 1; i++) {
      nx = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mt(D[nx][ny] * q, nx, ny));
        }
      }
    }
    ny = y + 2;
    for (ll i = x - 1; i <= x + 1; i++) {
      nx = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mt(D[nx][ny] * q, nx, ny));
        }
      }
    }
  }
}
int main() {
  cin >> H >> W;
  ll a, b, c, d;
  cin >> a >> b >> c >> d;
  a--;
  b--;
  c--;
  d--;
  S.resize(H);
  D.resize(H, vl(W, INF));
  for (i = 0; i < H; i++) {
    cin >> S[i];
  }
  bfs(a, b);
  if (D[c][d] == INF)
    cout << -1;
  else
    co(D[c][d]);
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using vl = vector<ll>;
using vll = vector<vl>;
using vlll = vector<vll>;
using vpll = vector<pll>;
using vs = vector<string>;
using tll = tuple<ll, ll, ll>;
using vtll = vector<tll>;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const ld PI = 3.1415926535897932;
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define co(i) cout << i << endl;
#define co2(i, j) cout << i << " " << j << endl;
#define co3(i) cout << i << " ";
#define po(i) cout << i.first << " " << i.second << endl;
void in() {}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail> void debug_out(Head h, Tail... t) {
  cerr << " " << h;
  if (sizeof...(t) > 0)
    cerr << " :";
  debug_out(t...);
}
template <typename T> ostream &operator<<(ostream &os, vector<T> vec) {
  for (size_t i = 0; i < vec.size(); i++)
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
ll ctoi(char c) {
  switch (c) {
  case '0':
    return 0;
  case '1':
    return 1;
  case '2':
    return 2;
  case '3':
    return 3;
  case '4':
    return 4;
  case '5':
    return 5;
  case '6':
    return 6;
  case '7':
    return 7;
  case '8':
    return 8;
  case '9':
    return 9;
  default:
    return 0;
  }
}
bool pairCompare(const pll firstElof, pll secondElof) {
  return firstElof.second < secondElof.second;
}
//**Snippetリスト**//
// rep, vin, all, iteLoop, bitSearch, bitList, nod, LIS, digitDP, treeDP,
// Rerooting// gcdlcm, isPrime, eratos, primeFactorize, Npow, combination,
// divisor, modinv, doubling// dfs, bfs, dijkstra, WarshallFloyd, BellmanFord,
// UnionFind, Kruskal, RMQ, LCA, FordFulkerson//
ll i, j, k, l;
ll N, M, K, H, W, L, X, Y, Z, R, Q, T;
ll MOD = 1000000007, INF = 1LL << 60, ans = 0, z = 0, o = 1;
vll flag, D;
vector<vpll> path;
vs S;
void bfs(ll x, ll y) {
  queue<pll> Q;
  Q.push(mp(x, y));
  D[x][y] = 0;
  pll u;
  while (!Q.empty()) {
    u = Q.front();
    ll x = u.first;
    ll y = u.second;
    Q.pop();
    ll nx = x, ny = y;
    nx = x - 1;
    ny = y;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mp(nx, ny));
      }
    }
    nx = x + 1;
    ny = y;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mp(nx, ny));
      }
    }
    nx = x;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mp(nx, ny));
      }
    }
    nx = x;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] < D[nx][ny]) {
        D[nx][ny] = D[x][y];
        Q.push(mp(nx, ny));
      }
    }
    // ここから魔法
    nx = x - 1;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mp(nx, ny));
      }
    }
    nx = x - 1;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mp(nx, ny));
      }
    }
    nx = x + 1;
    ny = y - 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mp(nx, ny));
      }
    }
    nx = x + 1;
    ny = y + 1;
    if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
      if (D[x][y] + 1 < D[nx][ny]) {
        D[nx][ny] = D[x][y] + 1;
        Q.push(mp(nx, ny));
      }
    }
    nx = x - 2;
    for (ll i = y - 2; i <= y + 2; i++) {
      ny = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mp(nx, ny));
        }
      }
    }
    nx = x + 2;
    for (ll i = y - 2; i <= y + 2; i++) {
      ny = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mp(nx, ny));
        }
      }
    }
    ny = y - 2;
    for (ll i = x - 1; i <= x + 1; i++) {
      nx = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mp(nx, ny));
        }
      }
    }
    ny = y + 2;
    for (ll i = x - 1; i <= x + 1; i++) {
      nx = i;
      if (nx >= 0 && nx < H && ny >= 0 && ny < W && S[nx][ny] == '.') {
        if (D[x][y] + 1 < D[nx][ny]) {
          D[nx][ny] = D[x][y] + 1;
          Q.push(mp(nx, ny));
        }
      }
    }
  }
}
int main() {
  cin >> H >> W;
  ll a, b, c, d;
  cin >> a >> b >> c >> d;
  a--;
  b--;
  c--;
  d--;
  S.resize(H);
  D.resize(H, vl(W, INF));
  for (i = 0; i < H; i++) {
    cin >> S[i];
  }
  bfs(a, b);
  if (D[c][d] == INF)
    cout << -1;
  else
    co(D[c][d]);
}