luogu_1379 八数码难题

八数码-->BFS+set

 #include<iostream>
 #include<cstdlib>
 #include<cstdio>
 #include<cstring>
 #include<set>
 using namespace std;
 struct aaa{
     int map[][];
     int dep,x,y;
 }que[];
 set<int> ssr;
 int head=,tail=;
 int dx[]={,,-,,};
 int dy[]={,,, ,-};
 int start[][];
 int goal[][]={{,,,},{,,,},{,,,},{,,,}};
 int temp[][];
 char putt[];
 long long ans;
 /*int judge()
 {
     int i,j,k;
     for(i=1;i<=tail;i++)
     {
         bool p=1;
         for(j=1;j<=3;j++)
             for(k=1;k<=3;k++)
                 if(que[i].map[j][k]!=temp[j][k])
                     p=0;
         if(p==1)
             return 0;
     }
     return 1;
 }*/

 int judge()
 {
     long long num=;
     int l,k;
     for(l=;l<=;l++)
         for(k=;k<=;k++)
             num=num*+temp[l][k];
     pair<set<int>::iterator,bool>f=ssr.insert(num);
     return f.second;
 }
 int win(){
     int i,j;
     for(i=;i<=;i++)
         for(j=;j<=;j++)
             if(temp[i][j]!=goal[i][j])
                 return ;
     return ;
 }
 void bfs()
 {
     int i,j;
     memcpy(temp,start,sizeof (start));
     if(win())
          return;
     memcpy(que[tail].map,start,sizeof (start));
     for(i=;i<=;i++)
         for(j=;j<=;j++)
         {
             if(start[i][j]==)
             {
                 que[tail].x=i;que[tail].y=j;
                 break;
             }
         }

     while(head<tail)
     {
         head++;
         for(i=;i<=;i++)
         {
             int newx=que[head].x+dx[i];
             int newy=que[head].y+dy[i];
             if(newx>=&&newy>=&&newx<=&&newy<=)
             {
                 memcpy(temp,que[head].map,sizeof(temp));//
                 swap(temp[newx][newy],temp[que[head].x][que[head].y]);
                 if(judge())
                 {
                     tail++;
                     que[tail].x=newx;
                     que[tail].y=newy;
                     memcpy(que[tail].map,temp,sizeof(temp));
                     que[tail].dep=que[head].dep+;
                     if(win())
                     {
                         ans=que[tail].dep;
                         return;
                     }
                 }
             }
         }
     }
 }
 int main()
 {
     int i,j;
     scanf("%s",putt);
     for(i=;i<=;i++)
         start[(i-)/+][(i-)%+]=putt[i-]-;
     bfs();
     printf("%d",ans);
     return ;
 }