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

/*input
4 5
1 2
2 5
#.###
####.
#..##
#..##
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    indexed_set;
#pragma GCC optimize("unroll-loops,no-stack-protector")
// order_of_key #of elements less than x
//  find_by_order kth element
typedef long long int ll;
#define ld double
#define pii pair<int, int>
#define f first
#define s second
#define pb push_back
#define REP(i, n) for (int i = 0; i < n; i++)
#define REP1(i, n) for (int i = 1; i <= n; i++)
#define FILL(n, x) memset(n, x, sizeof(n))
#define ALL(_a) _a.begin(), _a.end()
#define sz(x) (int)x.size()
const ll maxn = 1e3 + 5;
const ll maxlg = __lg(maxn) + 2;
const ll INF64 = 4e18;
const int INF = 0x3f3f3f3f;
const ll MOD = 1e9 + 7;
const ld PI = 3.14159265358979323846;
const ld eps = 1e-9;
#define lowb(x) x & (-x)
#define MNTO(x, y) x = min(x, (__typeof__(x))y)
#define MXTO(x, y) x = max(x, (__typeof__(x))y)
#define SORT_UNIQUE(c)                                                         \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define GET_POS(c, x) (lower_bound(c.begin(), c.end(), x) - c.begin())
#define MP make_pair
ll mult(ll a, ll b) { return (a * b) % MOD; }
ll mypow(ll a, ll b) {
  ll res = 1LL;
  while (b) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}
string arr[maxn];
int dist[maxn][maxn];
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
bool in[maxn][maxn];
int n, m;
bool isin(int x, int y) {
  if (x < 0 or x >= n or y < 0 or y >= m)
    return false;
  return true;
}
int32_t main() {
  ios::sync_with_stdio(false), cin.tie(0);

  cin >> n >> m;
  int sx, sy, ex, ey;
  cin >> sx >> sy >> ex >> ey;
  --sx;
  --sy;
  --ex;
  --ey;
  REP(i, n) cin >> arr[i];
  REP(i, n) REP(j, m) dist[i][j] = INF;
  dist[sx][sy] = 0;
  deque<pii> q;
  q.pb({sx, sy});
  while (!q.empty()) {
    pii z = q.front();
    q.pop_front();
    in[z.f][z.s] = 0;
    REP(i, 5) {
      REP(j, 5) {
        int x = z.f + i - 2, y = z.s + j - 2;
        if (isin(x, y) and arr[x][y] != '#' and
            dist[x][y] > dist[z.f][z.s] + 1) {
          dist[x][y] = dist[z.f][z.s] + 1;
          if (!in[x][y])
            q.pb({x, y}), in[x][y] = 1;
        }
      }
    }
    REP(k, 4) {
      int a = z.f + dx[k], b = z.s + dy[k];
      if (isin(a, b) and arr[a][b] != '#' and dist[a][b] > dist[z.f][z.s]) {
        dist[a][b] = dist[z.f][z.s];
        if (!in[a][b])
          q.push_front({a, b}), in[a][b] = 1;
      }
    }
  }
  if (dist[ex][ey] != INF)
    cout << dist[ex][ey];
  else
    cout << -1;
}


Error: TLE

Fixed submission:

/*input
4 5
1 2
2 5
#.###
####.
#..##
#..##
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    indexed_set;
#pragma GCC optimize("unroll-loops,no-stack-protector")
// order_of_key #of elements less than x
//  find_by_order kth element
typedef long long int ll;
#define ld double
#define pii pair<int, int>
#define f first
#define s second
#define pb push_back
#define REP(i, n) for (int i = 0; i < n; i++)
#define REP1(i, n) for (int i = 1; i <= n; i++)
#define FILL(n, x) memset(n, x, sizeof(n))
#define ALL(_a) _a.begin(), _a.end()
#define sz(x) (int)x.size()
const ll maxn = 1e3 + 5;
const ll maxlg = __lg(maxn) + 2;
const ll INF64 = 4e18;
const int INF = 0x3f3f3f3f;
const ll MOD = 1e9 + 7;
const ld PI = 3.14159265358979323846;
const ld eps = 1e-9;
#define lowb(x) x & (-x)
#define MNTO(x, y) x = min(x, (__typeof__(x))y)
#define MXTO(x, y) x = max(x, (__typeof__(x))y)
#define SORT_UNIQUE(c)                                                         \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define GET_POS(c, x) (lower_bound(c.begin(), c.end(), x) - c.begin())
#define MP make_pair
ll mult(ll a, ll b) { return (a * b) % MOD; }
ll mypow(ll a, ll b) {
  ll res = 1LL;
  while (b) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}
string arr[maxn];
int dist[maxn][maxn];
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
bool in[maxn][maxn];
int n, m;
bool isin(int x, int y) {
  if (x < 0 or x >= n or y < 0 or y >= m)
    return false;
  return true;
}
int32_t main() {
  ios::sync_with_stdio(false), cin.tie(0);

  cin >> n >> m;
  int sx, sy, ex, ey;
  cin >> sx >> sy >> ex >> ey;
  --sx;
  --sy;
  --ex;
  --ey;
  REP(i, n) cin >> arr[i];
  REP(i, n) REP(j, m) dist[i][j] = INF;
  dist[sx][sy] = 0;
  queue<pii> q;
  q.push({sx, sy});
  while (!q.empty()) {
    pii z = q.front();
    q.pop();
    in[z.f][z.s] = 0;
    REP(i, 5) {
      REP(j, 5) {
        int x = z.f + i - 2, y = z.s + j - 2;
        if (isin(x, y) and arr[x][y] != '#' and
            dist[x][y] > dist[z.f][z.s] + 1) {
          dist[x][y] = dist[z.f][z.s] + 1;
          if (!in[x][y])
            q.push({x, y}), in[x][y] = 1;
        }
      }
    }
    REP(k, 4) {
      int a = z.f + dx[k], b = z.s + dy[k];
      if (isin(a, b) and arr[a][b] != '#' and dist[a][b] > dist[z.f][z.s]) {
        dist[a][b] = dist[z.f][z.s];
        if (!in[a][b])
          q.push({a, b}), in[a][b] = 1;
      }
    }
  }
  if (dist[ex][ey] != INF)
    cout << dist[ex][ey];
  else
    cout << -1;
}