typedef int State[9];		//定义“状态”类型
const int Maxstate = 1000000;
State st[Maxstate],goal;	//状态数组
int dist[Maxstate];		
//如果要打印方案，还要定义一个父亲编号数组 int fa[Maxstate];

const int dx[]={-1,1,0,0};
const int dy[]={0,0,-1,1};

void init(){}		//初始化函数

int bfs()
{
	init();
	int front=1;
	int rear=2;
	while(front<rear)
	{
		State& s = st[front];
		if(memcmp(goal,s,sizeof(s))==0) return front;
		int z;
		for(z=0;z<9;z++) if(!s[z]) break;
		int x=z/3,y=z%3;
		for (int d=0;d<4;d++)
		{
			int newx=x+dx[d];
			int newy=y+dy[d];
			int newz=newx*3+newy;
			if(newx>=0 && newx<3 && newy>=0 &&newy<3)
			{
				State& t=st[rear];
				memcpy(&t,&s,sizeof(s));
				t[newz]=s[z];
				t[z]=s[newz];
				dist[rear]=dist[front]+1;
				if(insert(rear)) rear++;	//判重
			}
		}
		front++;
	}
	return 0;
}