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

// #define _GLIBCXX_DEBUG

#include <bits/stdc++.h>
using namespace std;

#define endl '\\n'
#define lfs cout << fixed << setprecision(10)
#define ALL(a) (a).begin(), (a).end()
#define ALLR(a) (a).rbegin(), (a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i, n, m) for (ll i = (n); i < (ll)(m); i++)
#define rrep(i, n, m) for (ll i = (ll)(m)-1; i >= (ll)(n); i--)
using ll = int;
using ld = long double;
const ll MOD1 = 1e9 + 7;
const ll MOD9 = 998244353;
const ll INF = 1e9;
using P = pair<ll, ll>;
template <typename T1, typename T2> bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  } else
    return false;
}
template <typename T1, typename T2> bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  } else
    return false;
}
ll median(ll a, ll b, ll c) {
  return a + b + c - max({a, b, c}) - min({a, b, c});
}
void ans1(bool x) {
  if (x)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
void ans2(bool x) {
  if (x)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
void ans3(bool x) {
  if (x)
    cout << "Yay!" << endl;
  else
    cout << ":(" << endl;
}
template <typename T1, typename T2> void ans(bool x, T1 y, T2 z) {
  if (x)
    cout << y << endl;
  else
    cout << z << endl;
}
template <typename T> void debug(vector<vector<T>> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    cout << v[i][0];
    for (ll j = 1; j < w; j++)
      cout spa v[i][j];
    cout << endl;
  }
};
void debug(vector<string> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w; j++)
      cout << v[i][j];
    cout << endl;
  }
};
template <typename T> void debug(vector<T> &v, ll n) {
  if (n != 0)
    cout << v[0];
  for (ll i = 1; i < n; i++)
    cout spa v[i];
  cout << endl;
};
template <typename T> vector<vector<T>> vec(ll x, ll y, T w) {
  vector<vector<T>> v(x, vector<T>(y, w));
  return v;
}
ll gcd(ll x, ll y) {
  ll r;
  while (y != 0 && (r = x % y) != 0) {
    x = y;
    y = r;
  }
  return y == 0 ? x : y;
}
vector<ll> dx = {1, -1, 0, 0, 1, 1, -1, -1};
vector<ll> dy = {0, 0, 1, -1, 1, -1, 1, -1};
template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << p.first << " " << p.second;
}
// mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
struct z {
  ll x, y, d;
  z(ll a, ll b, ll c) : x(a), y(b), d(c){};
};
int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res = 0, buf = 0;
  bool judge = true;
  int h, w, k;
  cin >> h >> w >> k;
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  x1--;
  y1--;
  x2--;
  y2--;
  vector<string> a(h);
  rep(i, 0, h) cin >> a[i];
  auto v = make_v(h, w, 4, MP(0, 0));
  rep(i, 0, h) rep(j, 0, w) rep(o, 0, 4) {
    int x = i + dx[o], y = j + dy[o];
    if (x < 0 || y < 0 || x >= h || y >= w)
      x = -1, y = -1;
    v[i][j][o] = MP(x, y);
  }
  queue<z> que;
  que.emplace(x1, y1, 0);
  auto dist = vec(h, w, INF);
  auto used = vec(h, w, false);
  // rep(i,0,h)rep(j,0,w)rep(o,0,4)cout<<i spa j spa o spa v[i][j][o]<<endl;

  while (!que.empty()) {
    auto p = que.front();
    que.pop();
    if (dist[p.x][p.y] != INF)
      continue;
    dist[p.x][p.y] = p.d;
    rep(i, 0, 4) {
      P q = MP(p.x, p.y);
      P nxt = q;
      while (1) {
        auto t = v[nxt.fi][nxt.se][i];
        nxt = t;
        if (t.fi == -1 || a[t.fi][t.se] == '@' ||
            abs(t.fi - p.x) + abs(t.se - p.y) > k)
          break;
      }
      while (1) {
        auto t = v[q.fi][q.se][i];
        v[q.fi][q.se][i] = nxt;
        if (t.fi == -1 || a[t.fi][t.se] == '@' ||
            abs(t.fi - p.x) + abs(t.se - p.y) > k)
          break;
        if (used[t.fi][t.se]) {
          q = t;
          continue;
        }
        used[t.fi][t.se] = true;
        q = t;
        que.emplace(t.fi, t.se, p.d + 1);
      }
    }
  }
  // debug(dist,h,w);
  ans(dist[x2][y2] == INF, -1, dist[x2][y2]);
  return 0;
}

Error: TLE

Fixed submission:

// #define _GLIBCXX_DEBUG

#include <bits/stdc++.h>
using namespace std;

#define endl '\\n'
#define lfs cout << fixed << setprecision(10)
#define ALL(a) (a).begin(), (a).end()
#define ALLR(a) (a).rbegin(), (a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i, n, m) for (ll i = (n); i < (ll)(m); i++)
#define rrep(i, n, m) for (ll i = (ll)(m)-1; i >= (ll)(n); i--)
using ll = int;
using ld = long double;
const ll MOD1 = 1e9 + 7;
const ll MOD9 = 998244353;
const ll INF = 1e9;
using P = pair<ll, ll>;
template <typename T1, typename T2> bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  } else
    return false;
}
template <typename T1, typename T2> bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  } else
    return false;
}
ll median(ll a, ll b, ll c) {
  return a + b + c - max({a, b, c}) - min({a, b, c});
}
void ans1(bool x) {
  if (x)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
void ans2(bool x) {
  if (x)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
void ans3(bool x) {
  if (x)
    cout << "Yay!" << endl;
  else
    cout << ":(" << endl;
}
template <typename T1, typename T2> void ans(bool x, T1 y, T2 z) {
  if (x)
    cout << y << endl;
  else
    cout << z << endl;
}
template <typename T> void debug(vector<vector<T>> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    cout << v[i][0];
    for (ll j = 1; j < w; j++)
      cout spa v[i][j];
    cout << endl;
  }
};
void debug(vector<string> &v, ll h, ll w) {
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w; j++)
      cout << v[i][j];
    cout << endl;
  }
};
template <typename T> void debug(vector<T> &v, ll n) {
  if (n != 0)
    cout << v[0];
  for (ll i = 1; i < n; i++)
    cout spa v[i];
  cout << endl;
};
template <typename T> vector<vector<T>> vec(ll x, ll y, T w) {
  vector<vector<T>> v(x, vector<T>(y, w));
  return v;
}
ll gcd(ll x, ll y) {
  ll r;
  while (y != 0 && (r = x % y) != 0) {
    x = y;
    y = r;
  }
  return y == 0 ? x : y;
}
vector<ll> dx = {1, -1, 0, 0, 1, 1, -1, -1};
vector<ll> dy = {0, 0, 1, -1, 1, -1, 1, -1};
template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << p.first << " " << p.second;
}
// mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
struct z {
  ll x, y, d;
  z(ll a, ll b, ll c) : x(a), y(b), d(c){};
};
int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res = 0, buf = 0;
  bool judge = true;
  int h, w, k;
  cin >> h >> w >> k;
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  x1--;
  y1--;
  x2--;
  y2--;
  vector<string> a(h);
  rep(i, 0, h) cin >> a[i];
  auto v = make_v(h, w, 4, MP(0, 0));
  rep(i, 0, h) rep(j, 0, w) rep(o, 0, 4) {
    int x = i + dx[o], y = j + dy[o];
    if (x < 0 || y < 0 || x >= h || y >= w)
      x = -1, y = -1;
    v[i][j][o] = MP(x, y);
  }
  queue<z> que;
  que.emplace(x1, y1, 0);
  auto dist = vec(h, w, INF);
  auto used = vec(h, w, false);
  // rep(i,0,h)rep(j,0,w)rep(o,0,4)cout<<i spa j spa o spa v[i][j][o]<<endl;

  while (!que.empty()) {
    auto p = que.front();
    que.pop();
    if (dist[p.x][p.y] != INF)
      continue;
    dist[p.x][p.y] = p.d;
    rep(i, 0, 4) {
      P q = MP(p.x, p.y);
      while (1) {
        auto t = v[q.fi][q.se][i];
        if (t.fi == -1 || a[t.fi][t.se] == '@' ||
            abs(t.fi - p.x) + abs(t.se - p.y) > k)
          break;
        if (used[t.fi][t.se]) {
          v[q.fi][q.se][i] = v[t.fi][t.se][i];
          continue;
        }
        used[t.fi][t.se] = true;
        q = t;
        que.emplace(t.fi, t.se, p.d + 1);
      }
    }
  }
  // debug(dist,h,w);
  ans(dist[x2][y2] == INF, -1, dist[x2][y2]);
  return 0;
}