Problem p02579 (C++) — buggy submission, verdict: Time Limit Exceeded

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

#define INF_LL (int64)1e18
#define INF (int32)1e9
#define REP(i, n) for (int64 i = 0; i < (n); i++)
#define FOR(i, a, b) for (int64 i = (a); i < (b); i++)
#define all(x) x.begin(), x.end()
#define fs first
#define sc second

using int32 = int_fast32_t;
using uint32 = uint_fast32_t;
using int64 = int_fast64_t;
using uint64 = uint_fast64_t;
using PII = pair<int32, int32>;
using PLL = pair<int64, int64>;

const double eps = 1e-10;

template <typename A, typename B> inline void chmin(A &a, B b) {
  if (a > b)
    a = b;
}
template <typename A, typename B> inline void chmax(A &a, B b) {
  if (a < b)
    a = b;
}

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 U, typename... V>
typename enable_if<is_same<T, U>::value != 0>::type fill_v(U &u, const V... v) {
  u = U(v...);
}

template <typename T, typename U, typename... V>
typename enable_if<is_same<T, U>::value == 0>::type fill_v(U &u, const V... v) {
  for (auto &e : u)
    fill_v<T>(e, v...);
}

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int64 H, W;
  cin >> H >> W;
  int64 Ch, Cw, Dh, Dw;
  cin >> Ch >> Cw >> Dh >> Dw;
  Ch--;
  Cw--;
  Dh--;
  Dw--;
  vector<string> S(H);
  REP(i, H) cin >> S[i];

  auto dy = vector<int>({-1, 0, 1, 0});
  auto dx = vector<int>({0, -1, 0, 1});

  auto in = [&](int y, int x) {
    return 0 <= y && y < H && 0 <= x && x < W && S[y][x] == '.';
  };

  auto d = make_v<int>(H, W);
  fill_v<int>(d, INF);

  d[Ch][Cw] = 0;

  using T = tuple<int, int, int>;
  deque<T> q;
  q.push_back({0, Ch, Cw});

  while (q.size()) {
    int c, y, x;
    tie(c, y, x) = q.front();
    q.pop_front();
    if (c > d[y][x])
      continue;
    REP(i, 4) {
      int yy = y + dy[i], xx = x + dx[i];
      if (!in(yy, xx))
        continue;
      if (d[yy][xx] > d[y][x]) {
        d[yy][xx] = d[y][x];
        q.emplace_front(d[yy][xx], yy, xx);
      }
    }
    FOR(cy, -2, 3) {
      FOR(cx, -2, 3) {
        int yy = y + cy, xx = x + cx;
        if (!in(yy, xx))
          continue;
        if (d[yy][xx] > d[y][x] + 1) {
          d[yy][xx] = d[y][x] + 1;
          q.emplace_back(d[yy][xx], yy, xx);
        }
      }
    }
  }
  if (d[Dh][Dw] == INF) {
    cout << -1 << endl;
  } else {
    cout << d[Dh][Dw] << endl;
  }
}


Error: TLE

Fixed submission:

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

#define INF_LL (int64)1e18
#define INF (int32)1e9
#define REP(i, n) for (int64 i = 0; i < (n); i++)
#define FOR(i, a, b) for (int64 i = (a); i < (b); i++)
#define all(x) x.begin(), x.end()
#define fs first
#define sc second

using int32 = int_fast32_t;
using uint32 = uint_fast32_t;
using int64 = int_fast64_t;
using uint64 = uint_fast64_t;
using PII = pair<int32, int32>;
using PLL = pair<int64, int64>;

const double eps = 1e-10;

template <typename A, typename B> inline void chmin(A &a, B b) {
  if (a > b)
    a = b;
}
template <typename A, typename B> inline void chmax(A &a, B b) {
  if (a < b)
    a = b;
}

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 U, typename... V>
typename enable_if<is_same<T, U>::value != 0>::type fill_v(U &u, const V... v) {
  u = U(v...);
}

template <typename T, typename U, typename... V>
typename enable_if<is_same<T, U>::value == 0>::type fill_v(U &u, const V... v) {
  for (auto &e : u)
    fill_v<T>(e, v...);
}

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int64 H, W;
  cin >> H >> W;
  int64 Ch, Cw, Dh, Dw;
  cin >> Ch >> Cw >> Dh >> Dw;
  Ch--;
  Cw--;
  Dh--;
  Dw--;
  vector<string> S(H);
  REP(i, H) cin >> S[i];

  auto dy = vector<int>({-1, 0, 1, 0});
  auto dx = vector<int>({0, -1, 0, 1});

  auto in = [&](int y, int x) {
    return 0 <= y && y < H && 0 <= x && x < W && S[y][x] == '.';
  };

  auto d = make_v<int>(H, W);
  fill_v<int>(d, INF);

  d[Ch][Cw] = 0;

  using T = tuple<int, int, int>;
  queue<T> q;
  q.push({0, Ch, Cw});

  while (q.size()) {
    int c, y, x;
    tie(c, y, x) = q.front();
    q.pop();
    if (c > d[y][x])
      continue;
    REP(i, 4) {
      int yy = y + dy[i], xx = x + dx[i];
      if (!in(yy, xx))
        continue;
      if (d[yy][xx] > d[y][x]) {
        d[yy][xx] = d[y][x];
        q.emplace(d[yy][xx], yy, xx);
      }
    }
    FOR(cy, -2, 3) {
      FOR(cx, -2, 3) {
        int yy = y + cy, xx = x + cx;
        if (!in(yy, xx))
          continue;
        if (d[yy][xx] > d[y][x] + 1) {
          d[yy][xx] = d[y][x] + 1;
          q.emplace(d[yy][xx], yy, xx);
        }
      }
    }
  }
  if (d[Dh][Dw] == INF) {
    cout << -1 << endl;
  } else {
    cout << d[Dh][Dw] << endl;
  }
}