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

/*بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيم*/

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
using namespace std;
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;
using pii = pair<int, int>;
const double PI = acos(-1.0);
const ll mod = 1e9 + 7;
// const ll mod = 998244353;

inline void normal(ll &a) {
  a %= mod;
  (a < 0) && (a += mod);
}
inline ll modMul(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  return (a * b) % mod;
}
inline ll modAdd(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  return (a + b) % mod;
}
inline ll modSub(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  a -= b;
  normal(a);
  return a;
}
inline ll modPow(ll b, ll p) {
  ll r = 1;
  while (p) {
    if (p & 1)
      r = modMul(r, b);
    b = modMul(b, b);
    p >>= 1;
  }
  return r;
}
inline ll modInverse(ll a) { return modPow(a, mod - 2); }
inline ll modDiv(ll a, ll b) { return modMul(a, modInverse(b)); }

#define si(x) scanf("%d", &x)
#define sii(x, y) scanf("%d %d", &x, &y)
#define siii(x, y, z) scanf("%d %d %d", &x, &y, &z)
#define sl(x) scanf("%lld", &x)
#define sll(x, y) scanf("%lld %lld", &x, &y)
#define slll(x, y, z) scanf("%lld %lld %lld", &x, &y, &z)
#define ss(ch) scanf("%s", ch)
#define pi(x) printf("%d", x)
#define pii(x, y) printf("%d %d", x, y)
#define piii(x, y, z) printf("%d %d %d", x, y, z)
#define pl(x) printf("%lld", x)
#define pll(x, y) printf("%lld %lld", x, y)
#define plll(x, y, z) printf("%lld %lld %lld", x, y, z)
#define ps(ch) printf("%s", ch)
#define F(i, a, b) for (int i = a; i <= b; i++)
#define R(i, b, a) for (int i = b; i >= a; i--)
#define REP(i, n) for (int i = 0; i < (n); i++)

int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1};
int dy8[] = {1, -1, -1, 0, 1, -1, 0, 1};
int kx8[] = {1, 1, 2, 2, -1, -1, -2, -2};
int ky8[] = {2, -2, 1, -1, 2, -2, 1, -1};
/* for Random Number generate
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
*/
///**
template <typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
#define dbg(args...)                                                           \\
  do {                                                                         \\
    cerr << #args << " : ";                                                    \\
    faltu(args);                                                               \\
  } while (0)
clock_t tStart = clock();
#define timeStamp                                                              \\
  dbg("Execution Time: ", (double)(clock() - tStart) / CLOCKS_PER_SEC)
void faltu() { cerr << endl; }
template <typename T> void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i)
    cerr << a[i] << ' ';
  cerr << endl;
}
template <typename T, typename... hello>
void faltu(T arg, const hello &...rest) {
  cerr << arg << ' ';
  faltu(rest...);
}

// Program showing a policy-based data structure.
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#include <functional> // for less
using namespace __gnu_pbds;

// GNU link : https://goo.gl/WVDL6g
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    new_data_set;
// find_by_order(k) – ফাংশনটি kth ordered element এর একটা পয়েন্টার রিটার্ন করে।
// অর্থাৎ তুমি চাইলেই kth ইন্ডেক্সে কি আছে, সেটা জেনে ফেলতে পারছো! order_of_key(x) –
// ফাংশনটি x এলিমেন্টটা কোন পজিশনে আছে সেটা বলে দেয়।
//*//**___________________________________________________**/
const int N = 1000006;

inline bool valid(int x, int y, int n, int m) {
  return (x >= 0 && x < n && y >= 0 && y < m);
}

int main() {
  FASTIO
  /*
#ifndef ONLINE_JUDGE
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
  freopen("error.txt", "w", stderr);
#endif
//*/
  int n, m, k;
  cin >> n >> m >> k;
  int x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  --x1;
  --x2;
  --y1;
  --y2;
  string g[n];
  for (int i = 0; i < n; i++) {
    cin >> g[i];
    // dbg(g[i]);
  }

  if (x1 == x2 && y1 == y2) {
    cout << "0\\n";
    return 0;
  }
  int dist[n][m];
  bool vis[n][m];
  memset(vis, false, sizeof vis);
  // memset(dist, 0, sizeof dist);

  queue<pii> Q;
  memset(dist, 0x3f, sizeof(dist));
  Q.push({x1, y1});
  vis[x1][y1] = true;
  dist[x1][y1] = 0;
  // k = min(k, max(n, m));
  while (!Q.empty()) {
    auto it = Q.front();
    Q.pop();
    int ux = it.first;
    int uy = it.second;

    for (int i = 0; i < 4; i++) {
      for (int j = 1; j <= k; j++) {
        int x = dx[i] * j + ux;
        int y = dy[i] * j + uy;
        if (!valid(x, y, n, m))
          break;
        if (g[x][y] == '@')
          break;
        if (dist[ux][uy] >= dist[x][y])
          break;
        if (vis[x][y])
          continue;
        vis[x][y] = true;
        dist[x][y] = dist[ux][uy] + 1;
        if (x == x2 && y == y2) {
          cout << dist[x][y] << "\\n";
          exit(0);
        }
        Q.push({x, y});
      }
    }
  }
  cout << "-1\\n";
  return 0;
}

Error: TLE

Fixed submission:

/*بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيم*/

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
using namespace std;
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;
using pii = pair<int, int>;
const double PI = acos(-1.0);
const ll mod = 1e9 + 7;
// const ll mod = 998244353;

inline void normal(ll &a) {
  a %= mod;
  (a < 0) && (a += mod);
}
inline ll modMul(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  return (a * b) % mod;
}
inline ll modAdd(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  return (a + b) % mod;
}
inline ll modSub(ll a, ll b) {
  a %= mod, b %= mod;
  normal(a), normal(b);
  a -= b;
  normal(a);
  return a;
}
inline ll modPow(ll b, ll p) {
  ll r = 1;
  while (p) {
    if (p & 1)
      r = modMul(r, b);
    b = modMul(b, b);
    p >>= 1;
  }
  return r;
}
inline ll modInverse(ll a) { return modPow(a, mod - 2); }
inline ll modDiv(ll a, ll b) { return modMul(a, modInverse(b)); }

#define si(x) scanf("%d", &x)
#define sii(x, y) scanf("%d %d", &x, &y)
#define siii(x, y, z) scanf("%d %d %d", &x, &y, &z)
#define sl(x) scanf("%lld", &x)
#define sll(x, y) scanf("%lld %lld", &x, &y)
#define slll(x, y, z) scanf("%lld %lld %lld", &x, &y, &z)
#define ss(ch) scanf("%s", ch)
#define pi(x) printf("%d", x)
#define pii(x, y) printf("%d %d", x, y)
#define piii(x, y, z) printf("%d %d %d", x, y, z)
#define pl(x) printf("%lld", x)
#define pll(x, y) printf("%lld %lld", x, y)
#define plll(x, y, z) printf("%lld %lld %lld", x, y, z)
#define ps(ch) printf("%s", ch)
#define F(i, a, b) for (int i = a; i <= b; i++)
#define R(i, b, a) for (int i = b; i >= a; i--)
#define REP(i, n) for (int i = 0; i < (n); i++)

int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1};
int dy8[] = {1, -1, -1, 0, 1, -1, 0, 1};
int kx8[] = {1, 1, 2, 2, -1, -1, -2, -2};
int ky8[] = {2, -2, 1, -1, 2, -2, 1, -1};
/* for Random Number generate
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
*/
///**
template <typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
#define dbg(args...)                                                           \\
  do {                                                                         \\
    cerr << #args << " : ";                                                    \\
    faltu(args);                                                               \\
  } while (0)
clock_t tStart = clock();
#define timeStamp                                                              \\
  dbg("Execution Time: ", (double)(clock() - tStart) / CLOCKS_PER_SEC)
void faltu() { cerr << endl; }
template <typename T> void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i)
    cerr << a[i] << ' ';
  cerr << endl;
}
template <typename T, typename... hello>
void faltu(T arg, const hello &...rest) {
  cerr << arg << ' ';
  faltu(rest...);
}

// Program showing a policy-based data structure.
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#include <functional> // for less
using namespace __gnu_pbds;

// GNU link : https://goo.gl/WVDL6g
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    new_data_set;
// find_by_order(k) – ফাংশনটি kth ordered element এর একটা পয়েন্টার রিটার্ন করে।
// অর্থাৎ তুমি চাইলেই kth ইন্ডেক্সে কি আছে, সেটা জেনে ফেলতে পারছো! order_of_key(x) –
// ফাংশনটি x এলিমেন্টটা কোন পজিশনে আছে সেটা বলে দেয়।
//*//**___________________________________________________**/
const int N = 1000006;

inline bool valid(int x, int y, int n, int m) {
  return (x >= 0 && x < n && y >= 0 && y < m);
}

int main() {
  FASTIO
  /*
#ifndef ONLINE_JUDGE
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
  freopen("error.txt", "w", stderr);
#endif
//*/
  int n, m, k;
  cin >> n >> m >> k;
  int x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  --x1;
  --x2;
  --y1;
  --y2;
  string g[n];
  for (int i = 0; i < n; i++) {
    cin >> g[i];
    // dbg(g[i]);
  }

  if (x1 == x2 && y1 == y2) {
    cout << "0\\n";
    return 0;
  }
  int dist[n][m];
  bool vis[n][m];
  memset(vis, false, sizeof vis);
  memset(dist, 0, sizeof dist);

  queue<pii> Q;
  Q.push({x1, y1});
  vis[x1][y1] = true;
  dist[x1][y1] = 0;

  while (!Q.empty()) {
    auto it = Q.front();
    Q.pop();
    int ux = it.first;
    int uy = it.second;

    for (int i = 0; i < 4; i++) {
      for (int j = 1; j <= k; j++) {
        int x = dx[i] * j + ux;
        int y = dy[i] * j + uy;
        if (!valid(x, y, n, m))
          break;
        if (g[x][y] == '@')
          break;
        if (vis[x][y])
          continue;
        vis[x][y] = true;
        dist[x][y] = dist[ux][uy] + 1;
        if (x == x2 && y == y2) {
          cout << dist[x][y] << "\\n";
          exit(0);
        }
        Q.push({x, y});
      }
    }
  }
  cout << "-1\\n";
  return 0;
}