UVa 10653 - Bombs! NO they are Mines!!

#include<cstdio>
#include<queue>
#include<cstring>
#include<cmath>
using namespace std;

// Accepted

#define sf scanf
#define pf printf

const int high = 2003;

int r  , c , adj[high][high] , cost[high][high];
int dir_x[4] = {1 , -1 , 0 , 0} , dir_y[4] = {0 , 0 , 1 , -1}; // Consider it as 4 direction co-ordinate
bool visited[high][high];

void BFS(int x , int y)
{
    queue<int>Q;

    Q.push(x);
    Q.push(y);

    adj[x][y] = -1;
    visited[x][y] = true;
    cost[x][y] = 0;

    while(!Q.empty())
    {
        int ux = Q.front();

        Q.pop();

        int uy = Q.front();

        Q.pop();

        for(int i=0; i<4; i++)
        {
           int vx = ux + dir_x[i];

            int vy = uy + dir_y[i];

            if((vx >= 0 && vx <= r) && (vy >= 0 && vy <= c) && (adj[vx][vy] == 0))
            {
                if(!visited[vx][vy] && !cost[vx][vy])
                {
                    visited[vx][vy] = true;
                    cost[vx][vy] = cost[ux][uy] + 1;
                    Q.push(vx);
                    Q.push(vy);
                }
            }
        }
    }
}

int main()
{
    int n , tr , tc , tn;

    while(~sf("%d %d", &r , &c))
    {
        if(!r && !c) break;

        memset(adj , 0 , sizeof adj);
        memset(cost , 0 , sizeof cost);
        memset(visited , false , sizeof visited);

        sf("%d", &n);

        for(int i=0; i<n; i++)
        {
            sf("%d %d" , &tr , &tn);

            while(tn--)
            {
                sf("%d", &tc);

                adj[tr][tc] = -1;
            }
        }

        int sr , sc , er , ec;
        sf("%d %d", &sr , &sc);
        sf("%d %d", &er , &ec);

        BFS(sr , sc);

        pf("%d\n" , cost[er][ec]);
    }

    return 0;
}