Problem p02644 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <cstdio>
#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 vpll = vector<pll>;
using vs = vector<string>;
using tll = tuple<ll, ll, ll>;
using vtll = vector<tll>;
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.first > secondElof.first;
}
//**Snippetリスト**//
// rep, vin, all, iteLoop, bitSearch, bitList, nod//
// gcdlcm, isPrime, eratos, primeFactorize, Npow, combination, divisor, modinv,
// doubling, digitDP// dfs, bfs, dijkstra, WarshallFloyd, BellmanFord,
// UnionFind, Kruskal, RMQ, LCA//
ll i, j, k, l;
ll N, M, K, H, W, L, X, Y, Z, R, Q;
ll MOD = 1000000007, INF = 1LL << 60, ans = 0, z = 0, o = 1;
vll flag, D;
vpll path;
vs C;
//***********//
void bfs(ll x, ll y) {
  queue<pll> Z;
  Z.push(mp(x, y));
  D[x][y] = 0;
  flag[x][y] = 1;
  pll u;
  while (!Z.empty()) {
    u = Z.front();
    flag[u.first][u.second] = 2;
    // debug(u.first, u.second,D[u.first][u.second]);
    Z.pop();
    ll nx, ny, px, py;
    ll cnt;
    px = u.first;
    py = u.second;
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge1");
    while (nx + 1 <= H - 1 && cnt > 0) {
      // debug(nx, ny);
      if (C[nx + 1][ny] == '@')
        break;
      if (flag[nx + 1][ny] == 2)
        break;
      if (D[px][py] + 1 <= D[nx + 1][ny]) {
        D[nx + 1][ny] = D[px][py] + 1;
        if (flag[nx + 1][ny] == 0)
          Z.push(mp(nx + 1, ny));
        flag[nx + 1][ny] = 1;
        nx++;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge2");
    while (nx - 1 >= 0 && cnt > 0) {
      if (C[nx - 1][ny] == '@')
        break;
      if (flag[nx - 1][ny] == 2)
        break;
      if (D[px][py] + 1 <= D[nx - 1][ny]) {
        D[nx - 1][ny] = D[px][py] + 1;
        if (flag[nx - 1][ny] == 0)
          Z.push(mp(nx - 1, ny));
        flag[nx - 1][ny] = 1;
        nx--;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge3");
    while (ny + 1 <= W - 1 && cnt > 0) {
      if (C[nx][ny + 1] == '@')
        break;
      if (flag[nx][ny + 1] == 2)
        break;
      if (D[px][py] + 1 <= D[nx][ny + 1]) {
        D[nx][ny + 1] = D[px][py] + 1;
        if (flag[nx][ny + 1] == 0)
          Z.push(mp(nx, ny + 1));
        flag[nx][ny + 1] = 1;
        ny++;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge4");
    while (ny - 1 >= 0 && cnt > 0) {
      if (C[nx][ny - 1] == '@')
        break;
      if (flag[nx][ny - 1] == 2)
        break;
      if (D[px][py] + 1 <= D[nx][ny - 1]) {
        D[nx][ny - 1] = D[px][py] + 1;
        if (flag[nx][ny - 1] == 0)
          Z.push(mp(nx, ny - 1));
        flag[nx][ny - 1] = 1;
        ny--;
        cnt--;
      } else
        cnt = 0;
    }
  }
}
int main() {
  cin >> H >> W >> K;
  ll P, Q, R, S;
  cin >> P >> Q >> R >> S;
  P--;
  Q--;
  R--;
  S--;
  C.resize(H);
  D.resize(H, vl(W));
  flag.resize(H, vl(W));
  for (i = 0; i < H; i++) {
    cin >> C[i];
    for (j = 0; j < W; j++) {
      D[i][j] = INF;
    }
  }
  bfs(P, Q);
  if (D[R][S] == INF)
    cout << -1;
  else
    cout << D[R][S];
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cstdio>
#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 vpll = vector<pll>;
using vs = vector<string>;
using tll = tuple<ll, ll, ll>;
using vtll = vector<tll>;
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.first > secondElof.first;
}
//**Snippetリスト**//
// rep, vin, all, iteLoop, bitSearch, bitList, nod//
// gcdlcm, isPrime, eratos, primeFactorize, Npow, combination, divisor, modinv,
// doubling, digitDP// dfs, bfs, dijkstra, WarshallFloyd, BellmanFord,
// UnionFind, Kruskal, RMQ, LCA//
ll i, j, k, l;
ll N, M, K, H, W, L, X, Y, Z, R, Q;
ll MOD = 1000000007, INF = 1LL << 60, ans = 0, z = 0, o = 1;
vll flag, D;
vpll path;
vs C;
//***********//
void bfs(ll x, ll y) {
  queue<pll> Z;
  Z.push(mp(x, y));
  D[x][y] = 0;
  flag[x][y] = 1;
  pll u;
  while (!Z.empty()) {
    u = Z.front();
    flag[u.first][u.second] = 1;
    // debug(u.first, u.second,D[u.first][u.second]);
    Z.pop();
    ll nx, ny, px, py;
    ll cnt;
    px = u.first;
    py = u.second;
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge1");
    while (nx + 1 <= H - 1 && cnt > 0) {
      // debug(nx, ny);
      if (C[nx + 1][ny] == '@')
        break;
      if (flag[nx + 1][ny])
        break;
      if (D[px][py] + 1 <= D[nx + 1][ny]) {
        D[nx + 1][ny] = D[px][py] + 1;
        Z.push(mp(nx + 1, ny));
        nx++;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge2");
    while (nx - 1 >= 0 && cnt > 0) {
      if (C[nx - 1][ny] == '@')
        break;
      if (flag[nx - 1][ny])
        break;
      if (D[px][py] + 1 <= D[nx - 1][ny]) {
        D[nx - 1][ny] = D[px][py] + 1;
        Z.push(mp(nx - 1, ny));
        nx--;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge3");
    while (ny + 1 <= W - 1 && cnt > 0) {
      if (C[nx][ny + 1] == '@')
        break;
      if (flag[nx][ny + 1])
        break;
      if (D[px][py] + 1 <= D[nx][ny + 1]) {
        D[nx][ny + 1] = D[px][py] + 1;
        Z.push(mp(nx, ny + 1));
        ny++;
        cnt--;
      } else
        cnt = 0;
    }
    nx = u.first;
    ny = u.second;
    cnt = K;
    // debug("hoge4");
    while (ny - 1 >= 0 && cnt > 0) {
      if (C[nx][ny - 1] == '@')
        break;
      if (flag[nx][ny - 1])
        break;
      if (D[px][py] + 1 <= D[nx][ny - 1]) {
        D[nx][ny - 1] = D[px][py] + 1;
        Z.push(mp(nx, ny - 1));
        ny--;
        cnt--;
      } else
        cnt = 0;
    }
  }
}
int main() {
  cin >> H >> W >> K;
  ll P, Q, R, S;
  cin >> P >> Q >> R >> S;
  P--;
  Q--;
  R--;
  S--;
  C.resize(H);
  D.resize(H, vl(W));
  flag.resize(H, vl(W));
  for (i = 0; i < H; i++) {
    cin >> C[i];
    for (j = 0; j < W; j++) {
      D[i][j] = INF;
    }
  }
  bfs(P, Q);
  if (D[R][S] == INF)
    cout << -1;
  else
    cout << D[R][S];
}