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

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
inline ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
template <class S, class T>
ostream &operator<<(ostream &out, const pair<S, T> &o) {
  out << "(" << o.first << "," << o.second << ")";
  return out;
}
template <class T> ostream &operator<<(ostream &out, const vector<T> &V) {
  for (int i = 0; i < V.size(); i++) {
    out << V[i];
    if (i != V.size() - 1)
      out << " ";
  }
  return out;
}
template <class T>
ostream &operator<<(ostream &out, const vector<vector<T>> &Mat) {
  for (int i = 0; i < Mat.size(); i++) {
    if (i != 0)
      out << endl;
    out << Mat[i];
  }
  return out;
}
template <class S, class T>
ostream &operator<<(ostream &out, const map<S, T> &mp) {
  out << "{ ";
  for (auto it = mp.begin(); it != mp.end(); it++) {
    out << it->first << ":" << it->second;
    if (mp.size() - 1 != distance(mp.begin(), it))
      out << ", ";
  }
  out << " }";
  return out;
}
template <typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
  t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}
/*
 <url:https://atcoder.jp/contests/abc170/tasks/abc170_f>
 問題文============================================================
 F - Pond Skater
 =================================================================
 解説=============================================================
 ================================================================
 */

template <class Type> Type solve(Type res = Type()) {
  int H, W, K;
  cin >> H >> W >> K;
  pii s, g;
  cin >> s.first >> s.second >> g.first >> g.second;
  s.first--;
  s.second--;
  g.first--;
  g.second--;
  auto c = make_v<char>(H, W);
  for (auto &vec : c)
    for (auto &in : vec)
      cin >> in;

  int dir[4] = {1, 0, -1, 0};
  auto dist = make_v<int>(H, W);
  fill_v(dist, INF);

  set<pii> st[2];
  int cur = 0, next = 1;
  st[cur].emplace(s);
  dist[s.first][s.second] = 0;
  while (st[cur].size()) {
    for (auto &p : st[cur]) {
      int x, y;
      tie(x, y) = p;
      for (int k = 0; k < 4; k++) {
        for (int cnt = 1; cnt <= K; cnt++) {
          int nx = x + dir[k] * cnt;
          int ny = y + dir[k ^ 1] * cnt;
          if (nx < 0 || nx >= H || ny < 0 || ny >= W)
            break;
          if (c[nx][ny] == '@')
            break;
          // if(dist[nx][ny] != INF) break;
          if (dist[nx][ny] <= dist[x][y])
            break;
          dist[nx][ny] = dist[x][y] + 1;
          st[next].emplace(nx, ny);
        }
      }
    }
    swap(cur, next);
    st[next].clear();
  }
  // cout << dist << endl;
  res = dist[g.first][g.second];

  if (res == INF)
    res = -1;
  return res;
}
int main(void) {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  // solve(0);
  cout << fixed << setprecision(15) << solve<ll>() << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
inline ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
template <class S, class T>
ostream &operator<<(ostream &out, const pair<S, T> &o) {
  out << "(" << o.first << "," << o.second << ")";
  return out;
}
template <class T> ostream &operator<<(ostream &out, const vector<T> &V) {
  for (int i = 0; i < V.size(); i++) {
    out << V[i];
    if (i != V.size() - 1)
      out << " ";
  }
  return out;
}
template <class T>
ostream &operator<<(ostream &out, const vector<vector<T>> &Mat) {
  for (int i = 0; i < Mat.size(); i++) {
    if (i != 0)
      out << endl;
    out << Mat[i];
  }
  return out;
}
template <class S, class T>
ostream &operator<<(ostream &out, const map<S, T> &mp) {
  out << "{ ";
  for (auto it = mp.begin(); it != mp.end(); it++) {
    out << it->first << ":" << it->second;
    if (mp.size() - 1 != distance(mp.begin(), it))
      out << ", ";
  }
  out << " }";
  return out;
}
template <typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
  t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}
/*
 <url:https://atcoder.jp/contests/abc170/tasks/abc170_f>
 問題文============================================================
 F - Pond Skater
 =================================================================
 解説=============================================================
 ================================================================
 */

template <class Type> Type solve(Type res = Type()) {
  int H, W, K;
  cin >> H >> W >> K;
  pii s, g;
  cin >> s.first >> s.second >> g.first >> g.second;
  s.first--;
  s.second--;
  g.first--;
  g.second--;
  auto c = make_v<char>(H, W);
  for (auto &vec : c)
    for (auto &in : vec)
      cin >> in;

  int dir[4] = {1, 0, -1, 0};
  auto dist = make_v<int>(H, W);
  fill_v(dist, INF);

  using Item = tuple<int, int, int>;
  queue<Item> q;
  q.emplace(s.first, s.second, 0);
  dist[s.first][s.second] = 0;
  while (q.size()) {
    int x, y, cost;
    tie(x, y, cost) = q.front();
    q.pop();
    if (dist[x][y] < cost)
      continue;
    ;
    for (int k = 0; k < 4; k++) {
      for (int cnt = 1; cnt <= K; cnt++) {
        int nx = x + dir[k] * cnt;
        int ny = y + dir[k ^ 1] * cnt;
        if (nx < 0 || nx >= H || ny < 0 || ny >= W)
          break;
        if (c[nx][ny] == '@')
          break;
        if (dist[nx][ny] > dist[x][y] + 1) {
          dist[nx][ny] = dist[x][y] + 1;
          q.emplace(nx, ny, dist[nx][ny]);
        }
      }
    }
  }
  res = dist[g.first][g.second];

  if (res == INF)
    res = -1;
  return res;
}
int main(void) {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  // solve(0);
  cout << fixed << setprecision(15) << solve<ll>() << endl;
  return 0;
}