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

#include <bits/stdc++.h>
#define For(i, a, b) for (int(i) = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int(i) = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> T div_floor(T a, T b) {
  if (b < 0)
    a *= -1, b *= -1;
  return a >= 0 ? a / b : (a + 1) / b - 1;
}
template <class T> T div_ceil(T a, T b) {
  if (b < 0)
    a *= -1, b *= -1;
  return a > 0 ? (a - 1) / b + 1 : a / b;
}

constexpr lint mod = 1000000007;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

struct state {
  int x, y, d;
  state(int x, int y, int d) : x(x), y(y), d(d) {}
};

int h, w;
int sx, sy, gx, gy;
char c[1010][1010];
int dist[1010][1010];
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

int main() {
  scanf("%d%d", &h, &w);
  scanf("%d%d%d%d", &sx, &sy, &gx, &gy);
  --sx;
  --sy;
  --gx;
  --gy;
  rep(i, h) rep(j, w) scanf(" %c", &c[i][j]);

  rep(i, h) rep(j, w) dist[i][j] = mod;
  deque<state> dq;
  dist[sx][sy] = 0;
  dq.emplace_back(sx, sy, 0);
  while (!dq.empty()) {
    auto s = dq.front();
    dq.pop_front();
    if (s.d > dist[s.x][s.y])
      continue;
    rep(i, 4) {
      int nx = s.x + dx[i], ny = s.y + dy[i];
      if (0 <= nx && nx < h && 0 <= ny && ny < w && c[nx][ny] == '.') {
        if (chmin(dist[nx][ny], s.d)) {
          dq.emplace_front(nx, ny, dist[nx][ny]);
        }
      }
    }
    for (int nx = s.x - 2; nx <= s.x + 2; ++nx) {
      for (int ny = s.y - 2; ny <= s.y + 2; ++ny) {
        if (0 <= nx && nx < h && 0 <= ny && ny < w && c[nx][ny] == '.') {
          if (chmin(dist[nx][ny], s.d + 1)) {
            dq.emplace_back(nx, ny, dist[nx][ny]);
          }
        }
      }
    }
  }

  printf("%d\\n", dist[gx][gy] == mod ? -1 : dist[gx][gy]);
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#define For(i, a, b) for (int(i) = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int(i) = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> T div_floor(T a, T b) {
  if (b < 0)
    a *= -1, b *= -1;
  return a >= 0 ? a / b : (a + 1) / b - 1;
}
template <class T> T div_ceil(T a, T b) {
  if (b < 0)
    a *= -1, b *= -1;
  return a > 0 ? (a - 1) / b + 1 : a / b;
}

constexpr lint mod = 1000000007;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

struct state {
  int x, y, d;
  state(int x, int y, int d) : x(x), y(y), d(d) {}
};

int h, w;
int sx, sy, gx, gy;
char c[1010][1010];
int dist[1010][1010];
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

int main() {
  scanf("%d%d", &h, &w);
  scanf("%d%d%d%d", &sx, &sy, &gx, &gy);
  --sx;
  --sy;
  --gx;
  --gy;
  rep(i, h) rep(j, w) scanf(" %c", &c[i][j]);

  rep(i, h) rep(j, w) dist[i][j] = mod;
  deque<state> dq;
  dist[sx][sy] = 0;
  dq.emplace_back(sx, sy, 0);
  while (!dq.empty()) {
    auto s = dq.front();
    dq.pop_front();
    if (s.d > dist[s.x][s.y])
      continue;
    rep(i, 4) {
      int nx = s.x + dx[i], ny = s.y + dy[i];
      if (0 <= nx && nx < h && 0 <= ny && ny < w && c[nx][ny] == '.') {
        if (chmin(dist[nx][ny], s.d)) {
          dq.emplace_front(nx, ny, dist[nx][ny]);
        }
      }
    }
    for (int nx = s.x - 2; nx <= s.x + 2; ++nx) {
      for (int ny = s.y - 2; ny <= s.y + 2; ++ny) {
        if (0 <= nx && nx < h && 0 <= ny && ny < w && c[nx][ny] == '.') {
          if (chmin(dist[nx][ny], s.d + 1)) {
            dq.emplace_front(nx, ny, dist[nx][ny]);
          }
        }
      }
    }
  }

  printf("%d\\n", dist[gx][gy] == mod ? -1 : dist[gx][gy]);
}