ADV-347 八数码
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef int State[9];
const int maxstate = 1000000;
State st[maxstate],goal;
int dist[maxstate];
const int hashsize = 1000003;
int head[hashsize],next[maxstate];
const int dx[]={
-1,1,0,0};
const int dy[]={
0,0,-1,1};
void init_lookup_table(){
memset(head,0,sizeof(head));
}
int hash(State &s){
int i,v=0;
for(i=0;i<9;i++)
v=v*10+s[i];
return v%hashsize;
}
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(){
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;
int d;
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;
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;
}
参考