八数码问题

 1 #include<stdio.h>

 2 #include<string.h>

 3 #include<set>

 4 #include<time.h>

 5 using namespace std;

 6 

 7 typedef int state[9];

 8 const int max=1000000;

 9 state st[max],goal;

10 int dist[max];

11 const int dx[]={-1,1,0,0};

12 const int dy[]={0,0,-1,1};

13 

14 struct cmp

15 {

16     bool operator ()(int a,int b)const

17     {

18         return memcmp(&st[a],&st[b],sizeof(st[b]))<0;

19     }

20 };

21 

22 set<int, cmp> vis;

23 

24 void in()

25 {

26     vis.clear();

27 }

28 

29 int insert(int s)

30 {

31     if(vis.count(s)) return 0;

32     vis.insert(s);

33     return 1;

34 }

35 

36 int bfs()

37 {

38     int front,rear,z,d,newy,newz,newx,x,y;

39     rear=2;

40     front=1;

41     //state s,t;

42     in();

43     while(front<rear)

44     {

45         state &s=st[front];

46         if(memcmp(goal,s,sizeof(s))==0) return front;

47         for(z=0;z<9;z++) if(!s[z]) break;

48         x=z/3;y=z%3;

49         for(d=0;d<4;d++)

50         {

51              newx=x+dx[d];

52              newy=y+dy[d];

53              newz=newx*3+newy;

54              if(newx>=0&&newx<3&&newy>=0&&newy<3)

55              {

56                 state &t=st[rear];

57                  memcpy(&t,&s,sizeof(s));

58                  t[newz]=s[z];

59                  t[z]=s[newz];

60                  dist[rear]=dist[front]+1;

61                  if(insert(rear)) rear++;

62              }

63         }

64         front++;

65     }

66     return 0;

67 }

68         

69 int main()

70 {

71     int i,ans;

72     for(i=0;i<9;i++) scanf("%d",&st[1][i]);

73     for(i=0;i<9;i++) scanf("%d",&goal[i]);

74     ans=bfs();

75     if(ans>0) printf("%d\n",dist[ans]);

76     else printf("-1\n");

77     printf("%d\n",clock()/CLOCKS_PER_SEC);

78     return 0;

79 }