Problem p02644 (C++)

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

// conversion
//------------------------------------------
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

// math
//-------------------------------------------
template <class T> inline T sqr(T x) { return x * x; }

// typedef
//------------------------------------------
typedef long long LL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
typedef priority_queue<int> PQGI; // 大きい順
typedef priority_queue<int, VI, greater<int>> PQLI;
typedef priority_queue<PII> PQGP;
typedef priority_queue<PII, VPII, greater<int>> PQLP;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EB emplace_back
#define PB push_back
#define PF push_front
#define POB pop_back
#define POF pop_front
#define MP make_pair
#define SZ(a) int((a).size())
#define SQ(a) ((a) * (a))
#define EACH(i, c)                                                             \
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())
#define SORTR(c) sort((c).rbegin(), (c).rend())
#define LB lower_bound
#define UB upper_bound
#define NEXP next_permutation
#define FI first
#define SE second
#define Vmin(a) *min_element((a).begin(), (a).end())
#define Vmax(a) *max_element((a).begin(), (a).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define FORR(i, a, b) for (int i = (b - 1); i >= (a); i--)
#define REPR(i, n) FORR(i, 0, n)
#define CFOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define CREP(i, n) CFOR(i, 0, n)
#define CFORR(i, a, b) for (int i = (b); i >= (a); i--)
#define CREPR(i, n) CFORR(i, 0, n)
#define BFOR(bit, a, b) for (int bit = (a); bit < (1 << (b)); ++bit)
#define BREP(bit, n) BFOR(bit, 0, n)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = INT_MAX / 2;
const LL LINF = LLONG_MAX / 3;
const int RINF = INT_MIN / 2;
const LL RLINF = LLONG_MIN / 3;
const LL MOD = 1e9 + 7;
const LL MODD = 998244353;
const int MAX = 510000;

inline bool Eq(double a, double b) { return fabs(b - a) < EPS; }

// other
//-------------------------------------------
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}

#define COUT(x) cout << (x) << endl
#define COUT2(x, y) cout << (x) << " " << (y) << endl
#define COUT3(x, y, z) cout << (x) << " " << (y) << " " << (z) << endl
#define PR(x) cout << (x)
#define ENDL cout << endl
#define SPACE cout << " "
#define BC(x) __builtin_popcountll(x)

VI dx = {1, 0, -1, 0, 1, 1, -1, -1};
VI dy = {0, 1, 0, -1, 1, -1, 1, -1};

LL Gcd(LL a, LL b) { return __gcd(a, b); }
LL Lcm(LL a, LL b) { return a / Gcd(a, b) * b; }

LL ModPow(LL A, LL N, LL M) {
  LL res = 1;
  while (N > 0) {
    if (N & 1)
      res = res * A % M;
    A = A * A % M;
    N >>= 1;
  }
  return res;
}

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

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

template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v)
    is >> in;
  return is;
}

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

struct node {
  int x, y, l;
  node(int x, int y, int l) : x(x), y(y), l(l){};
};

int main() {

  // cin.tie(0);
  // ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);

  int H, W, K;
  cin >> H >> W >> K;
  PII s, g;
  cin >> s >> g;
  s.FI--;
  s.SE--;
  g.FI--;
  g.SE--;

  VS C(H);
  cin >> C;

  VVI len(H, VI(W, INF));

  REP(i, H) REP(j, W) {
    if (C.at(i).at(j) == '@')
      len.at(i).at(j) = -1;
  }

  len.at(s.FI).at(s.SE) = 0;

  queue<node> qu;

  qu.emplace(s.FI, s.SE, 0);

  while (!qu.empty()) {
    node now = qu.front();
    qu.pop();
    REP(i, 4) {
      for (int t = 1; t <= K; t++) {
        int x = now.x + dx.at(i) * t;
        int y = now.y + dy.at(i) * t;
        if (x < 0 || H <= x || y < 0 || W <= y)
          break;
        if (len.at(x).at(y) >= now.l) {
          chmin(len.at(x).at(y), now.l + 1);
          qu.emplace(x, y, now.l + 1);
        } else {
          break;
        }
      }
    }
  }

  int ans = len.at(g.FI).at(g.SE);

  if (ans == INF)
    ans = -1;

  COUT(ans);

  //  REP(i,H)COUT(len.at(i));

  return 0;
}


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

// conversion
//------------------------------------------
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

// math
//-------------------------------------------
template <class T> inline T sqr(T x) { return x * x; }

// typedef
//------------------------------------------
typedef long long LL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
typedef priority_queue<int> PQGI; // 大きい順
typedef priority_queue<int, VI, greater<int>> PQLI;
typedef priority_queue<PII> PQGP;
typedef priority_queue<PII, VPII, greater<int>> PQLP;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EB emplace_back
#define PB push_back
#define PF push_front
#define POB pop_back
#define POF pop_front
#define MP make_pair
#define SZ(a) int((a).size())
#define SQ(a) ((a) * (a))
#define EACH(i, c)                                                             \
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())
#define SORTR(c) sort((c).rbegin(), (c).rend())
#define LB lower_bound
#define UB upper_bound
#define NEXP next_permutation
#define FI first
#define SE second
#define Vmin(a) *min_element((a).begin(), (a).end())
#define Vmax(a) *max_element((a).begin(), (a).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define FORR(i, a, b) for (int i = (b - 1); i >= (a); i--)
#define REPR(i, n) FORR(i, 0, n)
#define CFOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define CREP(i, n) CFOR(i, 0, n)
#define CFORR(i, a, b) for (int i = (b); i >= (a); i--)
#define CREPR(i, n) CFORR(i, 0, n)
#define BFOR(bit, a, b) for (int bit = (a); bit < (1 << (b)); ++bit)
#define BREP(bit, n) BFOR(bit, 0, n)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = INT_MAX / 2;
const LL LINF = LLONG_MAX / 3;
const int RINF = INT_MIN / 2;
const LL RLINF = LLONG_MIN / 3;
const LL MOD = 1e9 + 7;
const LL MODD = 998244353;
const int MAX = 510000;

inline bool Eq(double a, double b) { return fabs(b - a) < EPS; }

// other
//-------------------------------------------
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}

#define COUT(x) cout << (x) << endl
#define COUT2(x, y) cout << (x) << " " << (y) << endl
#define COUT3(x, y, z) cout << (x) << " " << (y) << " " << (z) << endl
#define PR(x) cout << (x)
#define ENDL cout << endl
#define SPACE cout << " "
#define BC(x) __builtin_popcountll(x)

VI dx = {1, 0, -1, 0, 1, 1, -1, -1};
VI dy = {0, 1, 0, -1, 1, -1, 1, -1};

LL Gcd(LL a, LL b) { return __gcd(a, b); }
LL Lcm(LL a, LL b) { return a / Gcd(a, b) * b; }

LL ModPow(LL A, LL N, LL M) {
  LL res = 1;
  while (N > 0) {
    if (N & 1)
      res = res * A % M;
    A = A * A % M;
    N >>= 1;
  }
  return res;
}

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

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

template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v)
    is >> in;
  return is;
}

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

struct node {
  int x, y, l;
  node(int x, int y, int l) : x(x), y(y), l(l){};
};

int main() {

  // cin.tie(0);
  // ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);

  int H, W, K;
  cin >> H >> W >> K;
  PII s, g;
  cin >> s >> g;
  s.FI--;
  s.SE--;
  g.FI--;
  g.SE--;

  VS C(H);
  cin >> C;

  VVI len(H, VI(W, INF));

  REP(i, H) REP(j, W) {
    if (C.at(i).at(j) == '@')
      len.at(i).at(j) = -1;
  }

  len.at(s.FI).at(s.SE) = 0;

  queue<node> qu;

  qu.emplace(s.FI, s.SE, 0);

  while (!qu.empty()) {
    node now = qu.front();
    qu.pop();
    REP(i, 4) {
      for (int t = 1; t <= K; t++) {
        int x = now.x + dx.at(i) * t;
        int y = now.y + dy.at(i) * t;
        if (x < 0 || H <= x || y < 0 || W <= y)
          break;
        if (len.at(x).at(y) > now.l) {
          if (chmin(len.at(x).at(y), now.l + 1)) {
            qu.emplace(x, y, now.l + 1);
          }
        } else {
          break;
        }
      }
    }
  }

  int ans = len.at(g.FI).at(g.SE);

  if (ans == INF)
    ans = -1;

  COUT(ans);

  //  REP(i,H)COUT(len.at(i));

  return 0;
}