luogu_1379 八数码难题

Posted 2021-02-09 oybdooo-ozai

八数码-->BFS+set

  1 #include<iostream>
  2 #include<cstdlib>
  3 #include<cstdio>
  4 #include<cstring>
  5 #include<set>
  6 using namespace std;
  7 struct aaa{
  8     int map[4][4];
  9     int dep,x,y;
 10 }que[370000];
 11 set<int> ssr;
 12 int head=0,tail=1;
 13 int dx[5]={0,1,-1,0,0};
 14 int dy[5]={0,0,0, 1,-1};
 15 int start[4][4];
 16 int goal[4][4]={{0,0,0,0},{0,1,2,3},{0,8,0,4},{0,7,6,5}};
 17 int temp[4][4];
 18 char putt[15];
 19 long long ans;
 20 /*int judge()
 21 {
 22     int i,j,k;
 23     for(i=1;i<=tail;i++)
 24     {
 25         bool p=1;
 26         for(j=1;j<=3;j++)
 27             for(k=1;k<=3;k++)
 28                 if(que[i].map[j][k]!=temp[j][k])
 29                     p=0;
 30         if(p==1)
 31             return 0;
 32     }
 33     return 1;
 34 }*/
 35 
 36 int judge()
 37 {
 38     long long num=0;
 39     int l,k;
 40     for(l=1;l<=3;l++)
 41         for(k=1;k<=3;k++)
 42             num=num*10+temp[l][k];
 43     pair<set<int>::iterator,bool>f=ssr.insert(num);
 44     return f.second;
 45 }
 46 int win(){
 47     int i,j;
 48     for(i=1;i<=3;i++)
 49         for(j=1;j<=3;j++)
 50             if(temp[i][j]!=goal[i][j])
 51                 return 0;
 52     return 1;
 53 }
 54 void bfs()
 55 {
 56     int i,j;
 57     memcpy(temp,start,sizeof (start));
 58     if(win())
 59          return;
 60     memcpy(que[tail].map,start,sizeof (start));
 61     for(i=1;i<=3;i++)
 62         for(j=1;j<=3;j++)
 63         {
 64             if(start[i][j]==0)
 65             {
 66                 que[tail].x=i;que[tail].y=j;
 67                 break;
 68             }
 69         }
 70             
 71             
 72     while(head<tail)
 73     {
 74         head++;
 75         for(i=1;i<=4;i++)
 76         {
 77             int newx=que[head].x+dx[i];
 78             int newy=que[head].y+dy[i];
 79             if(newx>=1&&newy>=1&&newx<=3&&newy<=3)
 80             {
 81                 memcpy(temp,que[head].map,sizeof(temp));//
 82                 swap(temp[newx][newy],temp[que[head].x][que[head].y]);
 83                 if(judge())
 84                 {
 85                     tail++;
 86                     que[tail].x=newx;
 87                     que[tail].y=newy;
 88                     memcpy(que[tail].map,temp,sizeof(temp));  
 89                     que[tail].dep=que[head].dep+1;
 90                     if(win())
 91                     {
 92                         ans=que[tail].dep;
 93                         return;
 94                     }
 95                 }
 96             }
 97         }
 98     }
 99 }
100 int main()
101 {
102     int i,j;
103     scanf("%s",putt);
104     for(i=1;i<=9;i++)
105         start[(i-1)/3+1][(i-1)%3+1]=putt[i-1]-48;
106     bfs();
107     printf("%d",ans);
108     return 0;
109 }