八数码问题

/*调用算法中函数求写一个排序*/
#include <iostream>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<string.h>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
#define maxn 2600000
typedef int State[9];
State st[maxn],goal;
int dist[maxn];
const int dx[]= {-1,1,0,0};
const int dy[]= {0,0,-1,1};
int vis[36288],fact[9];
/*void init_lookup_table()
{
    int i;
    fact[0]=1;
    for(i=0;i<9;i++)
    fact[i]=fact[i-1]*i;
}
int try_to_insert(int s)
{
    int code=0,i,j,cnt;//把st[s]映射到整数code
    for(i=0;i<9;i++)
    {
        cnt=0;
        for(j=i+1;j<9;j++)
        if(st[s][j]<st[s][i])
        cnt++;
        code+=fact[8-i]*cnt;
    }
    if(vis[code])
    return 0;
    return vis[code]=1;
}*/
const int MAXHASHSIZE  = 1000003;
int head[MAXHASHSIZE],next[maxn];
void init_lookup_table()
{
    memset(head,0,sizeof(head));
}
int hash(State & s)
{
    int v =0;
    for(int i=0; i<9; i++)
        v=v*10+s[i];
    return v % MAXHASHSIZE;
}
int try_to_insert(int s)
{
    int h=hash(st[s]);
    int u=head[h];
    while(u)
    {
        if(memcmp(st[u],st[s],sizeof(st[s]))==0)
            return 0;
        u=next[u];
    }
    next[s]=head[h];
    head[h]=s;
    return 1;
}
int bfs()
{
    int y,d;
    init_lookup_table();
    int front =1,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(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(try_to_insert(rear))
                    rear++;
            }
        }
        front++;
    }
    return 0;
}
int main()
{
    int i;
    while(1)
    {
        for(i=0; i<9; i++)
            scanf("%d",&st[1][i]);
        for(i=0; i<9; i++)
            scanf("%d",&goal[i]);
        int ans=bfs();
        if(ans>0)
            printf("%d\n",dist[ans]);
        else
            printf("-1\n");
    }
    return 0;
}
/*
2 6 4 1 3 7 0 5 8
8 1 5 7 3 6 4 0 2
31
*/