Problem p02644 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;

//////////////////////////////   Begin Macros

#define all(x) (x).begin(), (x).end()
#define rep(i, N) for (int i = 0; i < (int)(N); i++)
#define reprev(i, N) for (int i = (int)(N)-1; i >= 0; i--)
#define rep1(i, N) for (int i = 1; i <= (int)(N); i++)
#define rep1rev(i, N) for (int i = (int)(N); i >= 0; i--)
#define forbe(i, b, e) for (int i = (b); i < (e); i++)
#define forberev(i, b, e) for (int i = (e)-1; i >= (b); i--)
#define forfl(i, f, l) for (int i = (f); i <= (l); i++)
#define forflrev(i, f, l) for (int i = (l); i >= (f); i--)
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T> bool chmax(T &m, const T q) {
  if (m < q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T> bool chmin(T &m, const T q) {
  if (m > q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return {l.first + r.first, l.second + r.second};
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return {l.first - r.first, l.second - r.second};
}
template <typename T> pair<T, T> operator*(const pair<T, T> &l, const T &r) {
  return {l.first * r, l.second * r};
}
template <typename T> pair<T, T> operator/(const pair<T, T> &l, const T &r) {
  return {l.first / r, l.second / r};
}
template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec)
    is >> v;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) {
  os << "deq[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &pa) {
  is >> pa.first >> pa.second;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &pa) {
  os << "(" << pa.first << "," << pa.second << ")";
  return os;
}
template <typename... Ts>
istream &operator>>(istream &is, tuple<Ts...> &theTuple) {
  apply([&is](Ts &...tupleArgs) { ((is >> tupleArgs), ...); }, theTuple);
  return is;
}
template <typename... Ts>
ostream &operator<<(ostream &os, const tuple<Ts...> &theTuple) {
  apply(
      [&os](const Ts &...tupleArgs) {
        os << '(';
        size_t n(0);
        ((os << tupleArgs << (++n < sizeof...(Ts) ? "," : "")), ...);
        os << ')';
      },
      theTuple);
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}

template <typename T> void reset(vector<T> &v, const T reset_to) {
  for (auto &x : v)
    x = reset_to;
}
inline int popcount(const unsigned int x) { return __builtin_popcount(x); }
#define dbg(x)                                                                 \
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

ll nC2(ll n) { return n * (n - 1) / 2; }

const int intinf = numeric_limits<int>::max();
const ll llinf = numeric_limits<ll>::max();
const pii udlr[4] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

//////////////////////////////   End Macros

void solve() {
  int H, W, K;
  cin >> H >> W >> K;
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  x1--;
  y1--;
  x2--;
  y2--;
  vector<vector<char>> c(H, vector<char>(W));
  cin >> c;

  vector<vector<int>> d(H, vector<int>(W, -1));
  queue<pii> que;

  d[x1][y1] = 0;
  que.push({x1, y1});
  while (!que.empty()) {
    pii txy = que.front();
    que.pop();
    auto [tx, ty] = txy;
    int td = d[tx][ty];

    rep(i, 4) {
      pii nxy = txy;
      rep1(k, K) {
        nxy = nxy + udlr[i];
        auto [nx, ny] = nxy;
        if (not(0 <= nx and nx < H and 0 <= ny and ny < W))
          break;

        if (c[nx][ny] == '@')
          break;

        if (d[nx][ny] != -1)
          continue;

        d[nx][ny] = td + 1;
        que.push(nxy);
      }
    }
  }
  cout << d[x2][y2] << endl;
}

int main() {
  cerr << "start" << endl;
  // srand(time(0));
  cout << fixed << setprecision(15);

  solve();
  return 0;
}


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

//////////////////////////////   Begin Macros

#define all(x) (x).begin(), (x).end()
#define rep(i, N) for (int i = 0; i < (int)(N); i++)
#define reprev(i, N) for (int i = (int)(N)-1; i >= 0; i--)
#define rep1(i, N) for (int i = 1; i <= (int)(N); i++)
#define rep1rev(i, N) for (int i = (int)(N); i >= 0; i--)
#define forbe(i, b, e) for (int i = (b); i < (e); i++)
#define forberev(i, b, e) for (int i = (e)-1; i >= (b); i--)
#define forfl(i, f, l) for (int i = (f); i <= (l); i++)
#define forflrev(i, f, l) for (int i = (l); i >= (f); i--)
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T> bool chmax(T &m, const T q) {
  if (m < q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T> bool chmin(T &m, const T q) {
  if (m > q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return {l.first + r.first, l.second + r.second};
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return {l.first - r.first, l.second - r.second};
}
template <typename T> pair<T, T> operator*(const pair<T, T> &l, const T &r) {
  return {l.first * r, l.second * r};
}
template <typename T> pair<T, T> operator/(const pair<T, T> &l, const T &r) {
  return {l.first / r, l.second / r};
}
template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec)
    is >> v;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) {
  os << "deq[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &pa) {
  is >> pa.first >> pa.second;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &pa) {
  os << "(" << pa.first << "," << pa.second << ")";
  return os;
}
template <typename... Ts>
istream &operator>>(istream &is, tuple<Ts...> &theTuple) {
  apply([&is](Ts &...tupleArgs) { ((is >> tupleArgs), ...); }, theTuple);
  return is;
}
template <typename... Ts>
ostream &operator<<(ostream &os, const tuple<Ts...> &theTuple) {
  apply(
      [&os](const Ts &...tupleArgs) {
        os << '(';
        size_t n(0);
        ((os << tupleArgs << (++n < sizeof...(Ts) ? "," : "")), ...);
        os << ')';
      },
      theTuple);
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}

template <typename T> void reset(vector<T> &v, const T reset_to) {
  for (auto &x : v)
    x = reset_to;
}
inline int popcount(const unsigned int x) { return __builtin_popcount(x); }
#define dbg(x)                                                                 \
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

ll nC2(ll n) { return n * (n - 1) / 2; }

const int intinf = numeric_limits<int>::max();
const ll llinf = numeric_limits<ll>::max();
const pii udlr[4] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

//////////////////////////////   End Macros

void solve() {
  int H, W, K;
  cin >> H >> W >> K;
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  x1--;
  y1--;
  x2--;
  y2--;
  vector<vector<char>> c(H, vector<char>(W));
  cin >> c;

  vector<vector<int>> d(H, vector<int>(W, -1));
  queue<pii> que;

  d[x1][y1] = 0;
  que.push({x1, y1});
  while (!que.empty()) {
    pii txy = que.front();
    que.pop();
    auto [tx, ty] = txy;
    int td = d[tx][ty];

    rep(i, 4) {
      pii nxy = txy;
      rep1(k, K) {
        nxy = nxy + udlr[i];
        auto [nx, ny] = nxy;
        if (not(0 <= nx and nx < H and 0 <= ny and ny < W))
          break;

        if (c[nx][ny] == '@')
          break;

        if (d[nx][ny] != -1) {
          if (d[nx][ny] <= td)
            break;
          if (d[nx][ny] == td + 1)
            continue;
        }

        d[nx][ny] = td + 1;
        que.push(nxy);
      }
    }
  }
  cout << d[x2][y2] << endl;
}

int main() {
  cerr << "start" << endl;
  // srand(time(0));
  cout << fixed << setprecision(15);

  solve();
  return 0;
}