POJ 3322 Bloxorz

#include<cstring>
#include<algorithm>
#include<iostream>
#include<cstdio>
#include<queue>
#define de system("pause");
using namespace std;
int r,c;
char s[600][600];
int aim[5];
int ans=1000000;
bool bz[600][600][5];
bool check(int way,int x,int y)
{
    if(x<1||x>r||y<1||y>c)return 0;
    if(way==1)
    {
        if(s[x][y]=='#'||s[x][y+1]=='#')return 0;
        if(bz[x][y][1])return 0;
    }
    if(way==2)
    {
        if(s[x][y]=='#'||s[x+1][y]=='#')return 0;
        if(bz[x][y][2])return 0;
    }
    if(way==3)
    {
        if(s[x][y]=='#'||s[x][y]=='E')return 0;
        if(bz[x][y][3])return 0;
    }
    return 1;
}
struct node
{
    int way,x,y,step;
    node(int wa,int xx,int yy,int ste)
    {
        way=wa;
        x=xx;
        y=yy;
        step=ste;
    }
};
queue<node> q;
void so(int x,int y,int way,int step)
{
    bz[x][y][way]=1;
    q.push(node(way,x,y,step));
    if(way==3&&s[x][y]=='O')
    {
//        cout<<step<<endl;
        ans=min(ans,step);
    }
}
void bfs()
{
    while(!q.empty())
    {
        node now=q.front();
        int x=now.x,y=now.y,way=now.way,step=now.step;
        q.pop();
//        bz[x][y][way]=0;
        if(way==1)
        {
            if(check(1,x-1,y)) so(x-1,y,1,step+1);
            if(check(1,x+1,y)) so(x+1,y,1,step+1);
            if(check(3,x,y-1)) so(x,y-1,3,step+1);
            if(check(3,x,y+2)) so(x,y+2,3,step+1);            
        }
        if(way==2)
        {
            if(check(3,x-1,y)) so(x-1,y,3,step+1); 
            if(check(3,x+2,y)) so(x+2,y,3,step+1);
            if(check(2,x,y-1)) so(x,y-1,2,step+1);
            if(check(2,x,y+1)) so(x,y+1,2,step+1);
        }
        if(way==3)
        {
            if(check(2,x-2,y)) so(x-2,y,2,step+1);
            if(check(2,x+1,y)) so(x+1,y,2,step+1);
            if(check(1,x,y-2)) so(x,y-2,1,step+1);
            if(check(1,x,y+1)) so(x,y+1,1,step+1);
        }
        
    }
} 
int main()
{
    while(1)
    {
        while(q.size())q.pop();
        memset(bz,0,sizeof bz); 
        scanf("%d%d",&r,&c);
        if(r==0&&c==0)break;
        int a[10][3];
        int cnt=0;
        ans=1000000;
        for(int i=1;i<=r;++i)
        {
            scanf("%s",s[i]+1);
            for(int j=1;j<=c;j++)
            {
                if(s[i][j]=='X')
                {
                    ++cnt;
                    a[cnt][1]=i,a[cnt][2]=j;
                }
            }
        }
        if(cnt==1) q.push(node(3,a[cnt][1],a[cnt][2],0));
        else
        {
            if(a[1][1]==a[2][1]) q.push(node(1,a[1][1],a[1][2],0));
            else q.push(node(2,a[1][1],a[1][2],0));
        }
        bfs();
        if(ans==1000000)puts("Impossible");
        else cout<<ans<<endl;
    } 
    return 0;
}