代码:
#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
#define maxn 1010
char str[maxn][maxn];
struct node
{
friend bool operator < (node a,node b)
{
return a.num>b.num;
}
int x,y;
int num;
};
priority_queue<struct node> que;
int vis[maxn][maxn];
int sx,sy,tx,ty;
int dx[4]={-1,0,1,0};
int dy[4]={0,1,0,-1};
int row,cow;
int bfs()
{
int i;
while(que.size())
que.pop();
memset(vis,0,sizeof(vis));
struct node first={sx,sy,0};
que.push(first);
vis[sx][sy]=1;
while(que.size())
{
struct node now=que.top();
que.pop();
if(now.x==tx&&now.y==ty)
{
printf("%d\n",now.num);
return 1;
}
int nx,ny;
for(i=0;i<4;i++)
{
nx=now.x+dx[i];
ny=now.y+dy[i];
if(nx<=row&&nx>0&&ny>0&&ny<=cow&&!vis[nx][ny])
{
if(str[nx][ny]=='.')
{
struct node next={nx,ny,now.num+1};
que.push(next);
vis[nx][ny]=1;
}
else if(str[nx][ny]=='X')
{
struct node next={nx,ny,now.num};
que.push(next);
vis[nx][ny]=1;
}
}
}
}
return 0;
}
int main()
{
while(scanf("%d%d",&row,&cow)!=EOF)
{
if(!row&&!cow)
break;
int i;
for(i=1;i<=row;i++)
scanf("%s",&str[i][1]);
scanf("%d%d%d%d",&sx,&sy,&tx,&ty);
bfs();
}
return 0;
}