Problem p02644 (C++)

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

// template {{{
#define range(i, l, r) for (int i = (int)(l); i < (int)(r); (i) += 1)
#define rrange(i, l, r) for (int i = (int)(r)-1; i >= (int)(l); (i) -= 1)

#define whole(f, x, ...)                                                       \
  ([&](decltype((x)) container) {                                              \
    return (f)(begin(container), end(container), ##__VA_ARGS__);               \
  })(x)
#define rwhole(f, x, ...)                                                      \
  ([&](decltype((x)) container) {                                              \
    return (f)(rbegin(container), rend(container), ##__VA_ARGS__);             \
  })(x)

#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod = 1e9 + 7;
constexpr i32 inf = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

constexpr int dx[] = {0, -1, 1, 0, -1, 1, -1, 1};
constexpr int dy[] = {-1, 0, 0, 1, -1, -1, 1, 1};

struct IoSetup {
  IoSetup(int x = 15) {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(x);
    cerr << fixed << setprecision(x);
  }
} iosetup;

template <typename T = i64> T input() {
  T x;
  cin >> x;
  return x;
}

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) {
  range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); }
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v)
    is >> in;
  return is;
}

template <typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}

template <typename T> vector<T> make_vector(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_vector(size_t a, Ts... ts) {
  return vector<decltype(make_vector(ts...))>(a, make_vector(ts...));
}

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}
// }}}

void solver() {
  int h, w, k;
  cin >> h >> w >> k;

  int sy = input() - 1, sx = input() - 1, gy = input() - 1, gx = input() - 1;

  vector<string> cs(h);
  for (auto &c : cs)
    cin >> c;

  auto dp = make_vector(h, w, inf);
  dp[sy][sx] = 0;

  queue<pair<int, int>> que;
  que.emplace(sy, sx);
  auto used = make_vector(h, w, 2, false);

  while (!que.empty()) {
    auto p = que.front();
    que.pop();

    int x, y;
    tie(y, x) = p;

    range(d, 0, 4) {
      range(t, 1, k + 1) {
        int nx = x + dx[d] * t;
        int ny = y + dy[d] * t;
        if (nx < 0 || w <= nx || ny < 0 || h <= ny) {
          break;
        }

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

        if (dp[y][x] >= dp[ny][nx])
          break;

        dp[ny][nx] = dp[y][x] + 1;
        que.emplace(ny, nx);
      }
    }
  }

  if (dp[gy][gx] == inf) {
    cout << -1 << endl;
  } else {
    cout << dp[gy][gx] << endl;
  }
}

signed main(int argc, char *argv[]) { solver(); }


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

// template {{{
#define range(i, l, r) for (int i = (int)(l); i < (int)(r); (i) += 1)
#define rrange(i, l, r) for (int i = (int)(r)-1; i >= (int)(l); (i) -= 1)

#define whole(f, x, ...)                                                       \
  ([&](decltype((x)) container) {                                              \
    return (f)(begin(container), end(container), ##__VA_ARGS__);               \
  })(x)
#define rwhole(f, x, ...)                                                      \
  ([&](decltype((x)) container) {                                              \
    return (f)(rbegin(container), rend(container), ##__VA_ARGS__);             \
  })(x)

#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod = 1e9 + 7;
constexpr i32 inf = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

constexpr int dx[] = {0, -1, 1, 0, -1, 1, -1, 1};
constexpr int dy[] = {-1, 0, 0, 1, -1, -1, 1, 1};

struct IoSetup {
  IoSetup(int x = 15) {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(x);
    cerr << fixed << setprecision(x);
  }
} iosetup;

template <typename T = i64> T input() {
  T x;
  cin >> x;
  return x;
}

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) {
  range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); }
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v)
    is >> in;
  return is;
}

template <typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}

template <typename T> vector<T> make_vector(size_t a, T b) {
  return vector<T>(a, b);
}
template <typename... Ts> auto make_vector(size_t a, Ts... ts) {
  return vector<decltype(make_vector(ts...))>(a, make_vector(ts...));
}

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}
// }}}

void solver() {
  int h, w, k;
  cin >> h >> w >> k;

  int sy = input() - 1, sx = input() - 1, gy = input() - 1, gx = input() - 1;

  vector<string> cs(h);
  for (auto &c : cs)
    cin >> c;

  auto dp = make_vector(h, w, inf);
  dp[sy][sx] = 0;

  queue<pair<int, int>> que;
  que.emplace(sy, sx);
  auto used = make_vector(h, w, 2, false);

  while (!que.empty()) {
    auto p = que.front();
    que.pop();

    int x, y;
    tie(y, x) = p;

    range(d, 0, 4) {
      range(t, 1, k + 1) {
        int nx = x + dx[d] * t;
        int ny = y + dy[d] * t;
        if (nx < 0 || w <= nx || ny < 0 || h <= ny) {
          break;
        }

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

        if (dp[y][x] >= dp[ny][nx])
          break;

        if (dp[ny][nx] > dp[y][x] + 1) {
          dp[ny][nx] = dp[y][x] + 1;
          que.emplace(ny, nx);
        }
      }
    }
  }

  if (dp[gy][gx] == inf) {
    cout << -1 << endl;
  } else {
    cout << dp[gy][gx] << endl;
  }
}

signed main(int argc, char *argv[]) { solver(); }