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

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long int
using namespace __gnu_pbds;
typedef tree<pair<ll, pair<ll, ll>>, null_type, less<pair<ll, pair<ll, ll>>>,
             rb_tree_tag, tree_order_statistics_node_update>
    ordered_set;
#define me BOSS
#define bug() cout << "AIkahne aise" << endl
#define PI acos(-1)
/* Precode Start Here *\\
     Sieve
void sieve()
{
    for(ll i=3; i<=2000; i+=2)
    {
        for(ll j=i*i; j<=4000000; j+=i)
            A[j]=1;
    }
    v.push_back(2);
    for(ll i=3; i<=4000000; i+=2)
        if(A[i]==0)
            v.push_back(i);
}

     Power Function Modulo P

ll modPow(ll a, ll x, ll p) {
    //calculates a^x mod p in logarithmic time.
    long res = 1;
    while(x > 0) {
        if( x % 2 != 0) {
            res = (res * a) % p;
        }
        a = (a * a) % p;
        x /= 2;
    }
    return res;
}


   factorial

ll fact(ll n)
{
    ll ans=1;
    for(ll i=1;i<=n;i++)
    {
        ans=(ans*i)%mod;
    }
    return ans;
}
     Calculating nCr using Fermats law Theorem

ll modInverse(ll a, ll p) {
    //calculates the modular multiplicative of a mod m.
    //(assuming p is prime).
    return modPow(a, p-2, p);
}


ll modBinomial(ll n, ll k, ll p) {
// calculates C(n,k) mod p (assuming p is prime).

    ll numerator = 1; // n * (n-1) * ... * (n-k+1)
    for (ll i=0; i<k; i++) {
        numerator = (numerator * (n-i) ) % p;
    }

    ll denominator = 1; // k!
    for (ll i=1; i<=k; i++) {
        denominator = (denominator * i) % p;
    }

    // numerator / denominator mod p.
    return ( numerator* modInverse(denominator,p) ) % p;
}
     num of divisor and euler totient

ll phi[1000001],mark[1000001],divi[1000001];;
void divisorPhi(ll n)
{
    for(int i=1;i<=n;i++)
        phi[i]=i;
    for(int i=2;i<=n;i++)
    {
        if(!mark[i])
        {
            for(int j=i;j<=n;j+=i)
            {
                mark[j]=1;
                phi[j]*=(1-1/(double)i);
            }
        }
    }
    for(ll i=1;i<=n;i++)
    {
        for(ll j=i;j<=n;j+=i)
            divi[j]++;
    }
}
/* Precode Ends */
#define mod 1000000007
char A[1001][1001];
ll vis[1001][1001];
ll dis[1001][1001];
vector<ll> v;
map<ll, ll> myMap;
set<ll> mySet;
vector<pair<ll, ll>> vp;
priority_queue<ll> pq;
priority_queue<ll, vector<ll>, std::greater<ll>> first;
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, std::greater<pair<ll, ll>>>
    q;
ll po(ll a, ll n) {
  ll ans = 1;
  for (int i = 1; i <= n; i++)
    ans *= a;
  return ans;
}

ll r, c;
void go(int i, int j) {
  q.push(make_pair(i, j));
  vis[i][j] = 1;
  dis[i][j] = 0;
  while (!q.empty()) {
    ll u = q.top().first;
    ll v = q.top().second;
    q.pop();
    for (int x = -2; x <= 2; x++) {
      for (int y = -2; y <= 2; y++) {
        // cout<<u+x<<" "<<v+y<<endl;
        if (u + x > r || u + x < 1 || v + y > c || v + y < 1 ||
            (x == 0 && y == 0))
          continue;
        if (vis[u + x][v + y] == 0 && A[u + x][v + y] == '.') {
          vis[u + x][v + y] = 1;
          if (abs(x) + abs(y) > 1)
            dis[u + x][v + y] = dis[u][v] + 1;
          else
            dis[u + x][v + y] = dis[u][v];
          q.push(make_pair(u + x, v + y));
        } else if (A[u + x][v + y] == '.') {
          if ((abs(x) + abs(y) > 1) && dis[u + x][v + y] > dis[u][v] + 1) {
            dis[u + x][v + y] = dis[u][v] + 1;
            q.push(make_pair(u + x, v + y));
          } else if (dis[u][v] < dis[u + x][v + y] && (abs(x) + abs(y) <= 1)) {
            dis[u + x][v + y] = dis[u][v];
            q.push(make_pair(u + x, v + y));
          }
        }
      }
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  ll sx, sy, dx, dy;
  string s;
  cin >> r >> c;
  cin >> sx >> sy;
  cin >> dx >> dy;
  for (int i = 1; i <= r; i++) {
    cin >> s;
    for (int j = 1; j <= c; j++) {
      A[i][j] = s[j - 1];
      dis[i][j] = 99999999999999;
    }
  }
  go(sx, sy);
  //    for(int i=1; i<=r; i++)
  //    {
  //        for(int j=1; j<=c; j++)
  //        {
  //            // cout<<A[i][j]<<" ";
  //            cout<<dis[i][j]<<" ";
  //        }
  //        cout<<endl;
  //    }
  if (vis[dx][dy] == 0) {
    cout << -1 << endl;
  } else {
    cout << dis[dx][dy] << endl;
  }
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long int
using namespace __gnu_pbds;
typedef tree<pair<ll, pair<ll, ll>>, null_type, less<pair<ll, pair<ll, ll>>>,
             rb_tree_tag, tree_order_statistics_node_update>
    ordered_set;
#define me BOSS
#define bug() cout << "AIkahne aise" << endl
#define PI acos(-1)
/* Precode Start Here *\\
     Sieve
void sieve()
{
    for(ll i=3; i<=2000; i+=2)
    {
        for(ll j=i*i; j<=4000000; j+=i)
            A[j]=1;
    }
    v.push_back(2);
    for(ll i=3; i<=4000000; i+=2)
        if(A[i]==0)
            v.push_back(i);
}

     Power Function Modulo P

ll modPow(ll a, ll x, ll p) {
    //calculates a^x mod p in logarithmic time.
    long res = 1;
    while(x > 0) {
        if( x % 2 != 0) {
            res = (res * a) % p;
        }
        a = (a * a) % p;
        x /= 2;
    }
    return res;
}


   factorial

ll fact(ll n)
{
    ll ans=1;
    for(ll i=1;i<=n;i++)
    {
        ans=(ans*i)%mod;
    }
    return ans;
}
     Calculating nCr using Fermats law Theorem

ll modInverse(ll a, ll p) {
    //calculates the modular multiplicative of a mod m.
    //(assuming p is prime).
    return modPow(a, p-2, p);
}


ll modBinomial(ll n, ll k, ll p) {
// calculates C(n,k) mod p (assuming p is prime).

    ll numerator = 1; // n * (n-1) * ... * (n-k+1)
    for (ll i=0; i<k; i++) {
        numerator = (numerator * (n-i) ) % p;
    }

    ll denominator = 1; // k!
    for (ll i=1; i<=k; i++) {
        denominator = (denominator * i) % p;
    }

    // numerator / denominator mod p.
    return ( numerator* modInverse(denominator,p) ) % p;
}
     num of divisor and euler totient

ll phi[1000001],mark[1000001],divi[1000001];;
void divisorPhi(ll n)
{
    for(int i=1;i<=n;i++)
        phi[i]=i;
    for(int i=2;i<=n;i++)
    {
        if(!mark[i])
        {
            for(int j=i;j<=n;j+=i)
            {
                mark[j]=1;
                phi[j]*=(1-1/(double)i);
            }
        }
    }
    for(ll i=1;i<=n;i++)
    {
        for(ll j=i;j<=n;j+=i)
            divi[j]++;
    }
}
/* Precode Ends */
#define mod 1000000007
char A[1001][1001];
ll vis[1001][1001];
ll dis[1001][1001];
vector<ll> v;
map<ll, ll> myMap;
set<ll> mySet;
vector<pair<ll, ll>> vp;
priority_queue<ll> pq;
priority_queue<ll, vector<ll>, std::greater<ll>> first;
priority_queue<pair<ll, ll>> q;
ll po(ll a, ll n) {
  ll ans = 1;
  for (int i = 1; i <= n; i++)
    ans *= a;
  return ans;
}

ll r, c;
void go(int i, int j) {
  q.push(make_pair(i, j));
  vis[i][j] = 1;
  dis[i][j] = 0;
  while (!q.empty()) {
    ll u = q.top().first;
    ll v = q.top().second;
    q.pop();
    for (int x = -2; x <= 2; x++) {
      for (int y = -2; y <= 2; y++) {
        // cout<<u+x<<" "<<v+y<<endl;
        if (u + x > r || u + x < 1 || v + y > c || v + y < 1 ||
            (x == 0 && y == 0))
          continue;
        if (vis[u + x][v + y] == 0 && A[u + x][v + y] == '.') {
          vis[u + x][v + y] = 1;
          if (abs(x) + abs(y) > 1)
            dis[u + x][v + y] = dis[u][v] + 1;
          else
            dis[u + x][v + y] = dis[u][v];
          q.push(make_pair(u + x, v + y));
        } else if (A[u + x][v + y] == '.') {
          if ((abs(x) + abs(y) > 1) && dis[u + x][v + y] > dis[u][v] + 1) {
            dis[u + x][v + y] = dis[u][v] + 1;
            q.push(make_pair(u + x, v + y));
          } else if (dis[u][v] < dis[u + x][v + y] && (abs(x) + abs(y) <= 1)) {
            dis[u + x][v + y] = dis[u][v];
            q.push(make_pair(u + x, v + y));
          }
        }
      }
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  ll sx, sy, dx, dy;
  string s;
  cin >> r >> c;
  cin >> sx >> sy;
  cin >> dx >> dy;
  for (int i = 1; i <= r; i++) {
    cin >> s;
    for (int j = 1; j <= c; j++) {
      A[i][j] = s[j - 1];
      dis[i][j] = 99999999999999;
    }
  }
  go(sx, sy);
  //    for(int i=1; i<=r; i++)
  //    {
  //        for(int j=1; j<=c; j++)
  //        {
  //            // cout<<A[i][j]<<" ";
  //            cout<<dis[i][j]<<" ";
  //        }
  //        cout<<endl;
  //    }
  if (vis[dx][dy] == 0) {
    cout << -1 << endl;
  } else {
    cout << dis[dx][dy] << endl;
  }
  return 0;
}