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

#define DEBUG 0
/**
 * File    : F.cpp
 * Author  : Kazune Takahashi
 * Created : 6/20/2020, 5:31:40 AM
 * Powered by Visual Studio Code
 */
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// ----- boost -----
#include <boost/integer/common_factor_rt.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>
// ----- using directives and manipulations -----
using namespace std;
using boost::rational;
using boost::integer::gcd; // for C++14 or for cpp_int
using boost::integer::lcm; // for C++14 or for cpp_int
using boost::multiprecision::cpp_int;
using ll = long long;
using ld = long double;
template <typename T> using max_heap = priority_queue<T>;
template <typename T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
// ----- constexpr for Mint and Combination -----
constexpr ll MOD{1'000'000'007LL};
// constexpr ll MOD{998'244'353LL}; // be careful
constexpr ll MAX_SIZE{3'000'010LL};
// constexpr ll MAX_SIZE{30'000'010LL}; // if 10^7 is needed
// ----- ch_max and ch_min -----
template <typename T> bool ch_max(T &left, T right) {
  if (left < right) {
    left = right;
    return true;
  }
  return false;
}
template <typename T> bool ch_min(T &left, T right) {
  if (left > right) {
    left = right;
    return true;
  }
  return false;
}
// ----- Mint -----
template <ll MOD = MOD> class Mint {
public:
  ll x;
  Mint() : x{0LL} {}
  Mint(ll x) : x{(x % MOD + MOD) % MOD} {}
  Mint operator-() const { return x ? MOD - x : 0; }
  Mint &operator+=(Mint const &a) {
    if ((x += a.x) >= MOD) {
      x -= MOD;
    }
    return *this;
  }
  Mint &operator-=(Mint const &a) { return *this += -a; }
  Mint &operator++() { return *this += 1; }
  Mint operator++(int) {
    Mint tmp{*this};
    ++*this;
    return tmp;
  }
  Mint &operator--() { return *this -= 1; }
  Mint operator--(int) {
    Mint tmp{*this};
    --*this;
    return tmp;
  }
  Mint &operator*=(Mint const &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  Mint &operator/=(Mint const &a) {
    Mint b{a};
    return *this *= b.power(MOD - 2);
  }
  Mint operator+(Mint const &a) const { return Mint(*this) += a; }
  Mint operator-(Mint const &a) const { return Mint(*this) -= a; }
  Mint operator*(Mint const &a) const { return Mint(*this) *= a; }
  Mint operator/(Mint const &a) const { return Mint(*this) /= a; }
  bool operator<(Mint const &a) const { return x < a.x; }
  bool operator<=(Mint const &a) const { return x <= a.x; }
  bool operator>(Mint const &a) const { return x > a.x; }
  bool operator>=(Mint const &a) const { return x >= a.x; }
  bool operator==(Mint const &a) const { return x == a.x; }
  bool operator!=(Mint const &a) const { return !(*this == a); }
  Mint power(ll N) const {
    if (N == 0) {
      return 1;
    } else if (N % 2 == 1) {
      return *this * power(N - 1);
    } else {
      Mint half = power(N / 2);
      return half * half;
    }
  }
};
template <ll MOD> Mint<MOD> operator+(ll lhs, Mint<MOD> const &rhs) {
  return rhs + lhs;
}
template <ll MOD> Mint<MOD> operator-(ll lhs, Mint<MOD> const &rhs) {
  return -rhs + lhs;
}
template <ll MOD> Mint<MOD> operator*(ll lhs, Mint<MOD> const &rhs) {
  return rhs * lhs;
}
template <ll MOD> Mint<MOD> operator/(ll lhs, Mint<MOD> const &rhs) {
  return Mint<MOD>{lhs} / rhs;
}
template <ll MOD> istream &operator>>(istream &stream, Mint<MOD> &a) {
  return stream >> a.x;
}
template <ll MOD> ostream &operator<<(ostream &stream, Mint<MOD> const &a) {
  return stream << a.x;
}
// ----- Combination -----
template <ll MOD = MOD, ll MAX_SIZE = MAX_SIZE> class Combination {
public:
  vector<Mint<MOD>> inv, fact, factinv;
  Combination() : inv(MAX_SIZE), fact(MAX_SIZE), factinv(MAX_SIZE) {
    inv[1] = 1;
    for (auto i{2LL}; i < MAX_SIZE; i++) {
      inv[i] = (-inv[MOD % i]) * (MOD / i);
    }
    fact[0] = factinv[0] = 1;
    for (auto i{1LL}; i < MAX_SIZE; i++) {
      fact[i] = Mint<MOD>(i) * fact[i - 1];
      factinv[i] = inv[i] * factinv[i - 1];
    }
  }
  Mint<MOD> operator()(int n, int k) {
    if (n >= 0 && k >= 0 && n - k >= 0) {
      return fact[n] * factinv[k] * factinv[n - k];
    }
    return 0;
  }
  Mint<MOD> catalan(int x, int y) {
    return (*this)(x + y, y) - (*this)(x + y, y - 1);
  }
};
// ----- for C++14 -----
using mint = Mint<MOD>;
using combination = Combination<MOD, MAX_SIZE>;
// ----- for C++17 -----
template <typename T,
          typename enable_if<is_integral<T>::value>::type * = nullptr>
size_t popcount(T x) {
  return bitset<64>(x).count();
}
size_t popcount(string const &S) { return bitset<200010>{S}.count(); }
// ----- Infty -----
template <typename T> constexpr T Infty() { return numeric_limits<T>::max(); }
template <typename T> constexpr T mInfty() { return numeric_limits<T>::min(); }
// ----- frequently used constexpr -----
// constexpr double epsilon{1e-10};
// constexpr ll infty{1'000'000'000'000'010LL}; // or
// constexpr int infty{1'000'000'010};
constexpr int dx[4] = {1, 0, -1, 0};
constexpr int dy[4] = {0, 1, 0, -1};
// ----- Yes() and No() -----
void Yes() {
  cout << "Yes" << endl;
  exit(0);
}
void No() {
  cout << "No" << endl;
  exit(0);
}

// ----- Solve -----

using Info = tuple<int, int, int>;

class Solve {
  int H, W, K;
  int sx, sy, gx, gy;
  vector<string> c;
  vector<vector<int>> D;

public:
  Solve(int H, int W) : H{H}, W{W}, c(H), D(H, vector<int>(W, Infty<int>())) {
    cin >> K >> sx >> sy >> gx >> gy;
    --sx;
    --sy;
    --gx;
    --gy;
    for (auto q{0}; q < H; ++q) {
      cin >> c[q];
    }
  }

  void flush() {
    queue<Info> H;
    H.emplace(0, sx, sy);
    while (!H.empty()) {
      auto [d, src_x, src_y]{H.front()};
      H.pop();
      D[src_x][src_y] = d;
      for (auto k{0}; k < 4; ++k) {
        for (auto l{1}; l <= K; ++l) {
          auto dst_x{src_x + dx[k] * l};
          auto dst_y{src_y + dy[k] * l};
          if (!valid(dst_x, dst_y)) {
            break;
          }
          if (D[dst_x][dst_y] < d + 1) {
            break;
          }
          if (D[dst_x][dst_y] == d + 1) {
            continue;
          }
          D[dst_x][dst_y] = d + 1;
          H.emplace(d + 1, dst_x, dst_y);
        }
      }
    }
    auto ans{D[gx][gy]};
    if (ans == Infty<int>()) {
      ans = -1;
    }
    cout << ans << endl;
  }

private:
  bool valid(int x, int y) {
    return 0 <= x && x < H && 0 <= y && y < W && c[x][y] != '@';
  }
};

// ----- main() -----

int main() {
  int H, W;
  cin >> H >> W;
  Solve solve(H, W);
  solve.flush();
}


Error: TLE

Fixed submission:

#define DEBUG 0
/**
 * File    : F.cpp
 * Author  : Kazune Takahashi
 * Created : 6/20/2020, 5:31:40 AM
 * Powered by Visual Studio Code
 */
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// ----- boost -----
#include <boost/integer/common_factor_rt.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>
// ----- using directives and manipulations -----
using namespace std;
using boost::rational;
using boost::integer::gcd; // for C++14 or for cpp_int
using boost::integer::lcm; // for C++14 or for cpp_int
using boost::multiprecision::cpp_int;
using ll = long long;
using ld = long double;
template <typename T> using max_heap = priority_queue<T>;
template <typename T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
// ----- constexpr for Mint and Combination -----
constexpr ll MOD{1'000'000'007LL};
// constexpr ll MOD{998'244'353LL}; // be careful
constexpr ll MAX_SIZE{3'000'010LL};
// constexpr ll MAX_SIZE{30'000'010LL}; // if 10^7 is needed
// ----- ch_max and ch_min -----
template <typename T> bool ch_max(T &left, T right) {
  if (left < right) {
    left = right;
    return true;
  }
  return false;
}
template <typename T> bool ch_min(T &left, T right) {
  if (left > right) {
    left = right;
    return true;
  }
  return false;
}
// ----- Mint -----
template <ll MOD = MOD> class Mint {
public:
  ll x;
  Mint() : x{0LL} {}
  Mint(ll x) : x{(x % MOD + MOD) % MOD} {}
  Mint operator-() const { return x ? MOD - x : 0; }
  Mint &operator+=(Mint const &a) {
    if ((x += a.x) >= MOD) {
      x -= MOD;
    }
    return *this;
  }
  Mint &operator-=(Mint const &a) { return *this += -a; }
  Mint &operator++() { return *this += 1; }
  Mint operator++(int) {
    Mint tmp{*this};
    ++*this;
    return tmp;
  }
  Mint &operator--() { return *this -= 1; }
  Mint operator--(int) {
    Mint tmp{*this};
    --*this;
    return tmp;
  }
  Mint &operator*=(Mint const &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  Mint &operator/=(Mint const &a) {
    Mint b{a};
    return *this *= b.power(MOD - 2);
  }
  Mint operator+(Mint const &a) const { return Mint(*this) += a; }
  Mint operator-(Mint const &a) const { return Mint(*this) -= a; }
  Mint operator*(Mint const &a) const { return Mint(*this) *= a; }
  Mint operator/(Mint const &a) const { return Mint(*this) /= a; }
  bool operator<(Mint const &a) const { return x < a.x; }
  bool operator<=(Mint const &a) const { return x <= a.x; }
  bool operator>(Mint const &a) const { return x > a.x; }
  bool operator>=(Mint const &a) const { return x >= a.x; }
  bool operator==(Mint const &a) const { return x == a.x; }
  bool operator!=(Mint const &a) const { return !(*this == a); }
  Mint power(ll N) const {
    if (N == 0) {
      return 1;
    } else if (N % 2 == 1) {
      return *this * power(N - 1);
    } else {
      Mint half = power(N / 2);
      return half * half;
    }
  }
};
template <ll MOD> Mint<MOD> operator+(ll lhs, Mint<MOD> const &rhs) {
  return rhs + lhs;
}
template <ll MOD> Mint<MOD> operator-(ll lhs, Mint<MOD> const &rhs) {
  return -rhs + lhs;
}
template <ll MOD> Mint<MOD> operator*(ll lhs, Mint<MOD> const &rhs) {
  return rhs * lhs;
}
template <ll MOD> Mint<MOD> operator/(ll lhs, Mint<MOD> const &rhs) {
  return Mint<MOD>{lhs} / rhs;
}
template <ll MOD> istream &operator>>(istream &stream, Mint<MOD> &a) {
  return stream >> a.x;
}
template <ll MOD> ostream &operator<<(ostream &stream, Mint<MOD> const &a) {
  return stream << a.x;
}
// ----- Combination -----
template <ll MOD = MOD, ll MAX_SIZE = MAX_SIZE> class Combination {
public:
  vector<Mint<MOD>> inv, fact, factinv;
  Combination() : inv(MAX_SIZE), fact(MAX_SIZE), factinv(MAX_SIZE) {
    inv[1] = 1;
    for (auto i{2LL}; i < MAX_SIZE; i++) {
      inv[i] = (-inv[MOD % i]) * (MOD / i);
    }
    fact[0] = factinv[0] = 1;
    for (auto i{1LL}; i < MAX_SIZE; i++) {
      fact[i] = Mint<MOD>(i) * fact[i - 1];
      factinv[i] = inv[i] * factinv[i - 1];
    }
  }
  Mint<MOD> operator()(int n, int k) {
    if (n >= 0 && k >= 0 && n - k >= 0) {
      return fact[n] * factinv[k] * factinv[n - k];
    }
    return 0;
  }
  Mint<MOD> catalan(int x, int y) {
    return (*this)(x + y, y) - (*this)(x + y, y - 1);
  }
};
// ----- for C++14 -----
using mint = Mint<MOD>;
using combination = Combination<MOD, MAX_SIZE>;
// ----- for C++17 -----
template <typename T,
          typename enable_if<is_integral<T>::value>::type * = nullptr>
size_t popcount(T x) {
  return bitset<64>(x).count();
}
size_t popcount(string const &S) { return bitset<200010>{S}.count(); }
// ----- Infty -----
template <typename T> constexpr T Infty() { return numeric_limits<T>::max(); }
template <typename T> constexpr T mInfty() { return numeric_limits<T>::min(); }
// ----- frequently used constexpr -----
// constexpr double epsilon{1e-10};
// constexpr ll infty{1'000'000'000'000'010LL}; // or
// constexpr int infty{1'000'000'010};
constexpr int dx[4] = {1, 0, -1, 0};
constexpr int dy[4] = {0, 1, 0, -1};
// ----- Yes() and No() -----
void Yes() {
  cout << "Yes" << endl;
  exit(0);
}
void No() {
  cout << "No" << endl;
  exit(0);
}

// ----- Solve -----

using Info = tuple<int, int, int>;

class Solve {
  int H, W, K;
  int sx, sy, gx, gy;
  vector<string> c;
  vector<vector<int>> D;

public:
  Solve(int H, int W) : H{H}, W{W}, c(H), D(H, vector<int>(W, Infty<int>())) {
    cin >> K >> sx >> sy >> gx >> gy;
    --sx;
    --sy;
    --gx;
    --gy;
    for (auto q{0}; q < H; ++q) {
      cin >> c[q];
    }
  }

  void flush() {
    min_heap<Info> H;
    H.emplace(0, sx, sy);
    while (!H.empty()) {
      auto [d, src_x, src_y]{H.top()};
      H.pop();
      if (D[src_x][src_y] == Infty<int>()) {
        D[src_x][src_y] = d;
        for (auto k{0}; k < 4; ++k) {
          for (auto l{1}; l <= K; ++l) {
            auto dst_x{src_x + dx[k] * l};
            auto dst_y{src_y + dy[k] * l};
            if (!valid(dst_x, dst_y)) {
              break;
            }
            if (D[dst_x][dst_y] < d + 1) {
              break;
            }
            if (D[dst_x][dst_y] == d + 1) {
              continue;
            }
            H.emplace(d + 1, dst_x, dst_y);
          }
        }
      }
    }
    auto ans{D[gx][gy]};
    if (ans == Infty<int>()) {
      ans = -1;
    }
    cout << ans << endl;
  }

private:
  bool valid(int x, int y) {
    return 0 <= x && x < H && 0 <= y && y < W && c[x][y] != '@';
  }
};

// ----- main() -----

int main() {
  int H, W;
  cin >> H >> W;
  Solve solve(H, W);
  solve.flush();
}