poj 1077 hdu 1043 八数码

看了网上hdu的题的代码，反向搜索打表，试了一下结果MLE了，重新写一发

#include <iostream>
#include <queue>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
using namespace std;
struct step{
int ch[10];
int o;
int stata;
}a,b;
int vis[400000]={0};
int pre[400000];
int d[4][2]={1,0, -1,0, 0,1, 0,-1};
int aim=46234;
char mov[5]={"udlr"};
int fac[]={1,1,2,6,24,120,720,5040,40320,362880};//康拖展开判重
int cantor(int sss[])//康拖展开求该序列的hash值
{
int sum=0;
for(int i=0;i<9;i++)
{
int num=0;
for(int j=i+1;j<9;j++)
if(sss[j]<sss[i])num++;
sum+=(num*fac[9-i-1]);
}
return sum+1;
}
void bfs(){
memset(vis,-1,sizeof(vis));
memset(pre,-1,sizeof(pre));
for(int i=0;i<8;i++)a.ch[i]=i+1;
a.ch[8]=0;
a.o=8;
a.stata=cantor(a.ch);
vis[a.stata]=-2;
queue<step>qu;
qu.push(a);
while(!qu.empty()){
a=qu.front();
qu.pop();
int x=a.o/3,y=a.o%3;
for(int i=0;i<4;i++){
int xx=x+d[i][0];
int yy=y+d[i][1];
if(xx<0||xx>2||yy<0||yy>2)continue ;
b=a;
b.o=xx*3+yy;
swap(b.ch[b.o],b.ch[a.o]);
b.stata=cantor(b.ch);
if(vis[b.stata]==-1){
vis[b.stata]=i;
pre[b.stata]=a.stata;
qu.push(b);
}
}
}
}
void output(int out){
string ans;
ans.clear();
int nxt=out;
while(pre[nxt]!=-1){
switch(vis[nxt]){
case 0:ans+='u';break;
case 1:ans+='d';break;
case 2:ans+='l';break;
case 3:ans+='r';break;
}
nxt=pre[nxt];
}
cout<<ans<<endl;
}
char c;
int ii=0;
int main(){
bfs();
while(cin>>c){
if(c=='x'){
a.o=ii;
a.ch[ii]=0;
}
else a.ch[ii]=c-'0';
for(ii=1;ii<9;ii++){
cin>>c;
if(c=='x'){
a.o=ii;
a.ch[ii]=0;
}
else a.ch[ii]=c-'0';
}
int out=cantor(a.ch);
if(vis[out]==-1)cout<<"unsolvable"<<endl;
else output(out);
ii=0;
}
return 0;
}