HDU1195 BFS

题意：从一个4位数到另一个4位数 所需的步数

bfs

View Code

 1 #include<stdio.h>

 2 #include<string>

 3 #include<stdlib.h>

 4 #include<queue>

 5 #include<algorithm>

 6 #include<iostream>

 7 #include<map>

 8 using namespace std;

 9 const int maxn = 10;

10 char a[maxn],b[maxn];

11 int vis[ 100000 ];

12 struct node{

13     char nn[maxn];

14     int t;

15 };

16 

17 int solve( char a,char b,char c, char d ){

18     return (a-'0')*1+(b-'0')*10+(c-'0')*100+(d-'0')*1000;

19 }

20 

21 int bfs(){

22     queue<node>q;

23     while( !q.empty() )

24         q.pop();

25     node now,next;

26     memset( vis,0,sizeof( vis ));

27     strcpy( now.nn,a );//now.nn=a;

28     vis[ solve(a[0],a[1],a[2],a[3]) ]=1;

29     now.t=0;

30     q.push( now );

31     while( !q.empty() ){

32         now=q.front(),q.pop();

33         //printf("now:%s\n",now.nn);

34         if( solve(now.nn[0],now.nn[1],now.nn[2],now.nn[3]) == solve( b[0],b[1],b[2],b[3] ) )

35             return now.t;

36         //next.nn=now.nn;

37         next.t=now.t+1;

38         for( int i=0;i<4;i++ ){

39             strcpy( next.nn,now.nn );//.nn=now.nn;

40             if( next.nn[i]=='9' ){

41                 next.nn[i]='1';

42             }

43             else{

44                 next.nn[i]=now.nn[i]+1;

45             }

46             if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){

47                 vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;

48                 q.push( next );

49             }

50         }//add 1

51         for( int i=0;i<4;i++ ){

52             strcpy( next.nn,now.nn );//next.nn=now.nn;

53             if( next.nn[i]=='1' ){

54                 next.nn[i]='9';

55             }

56             else{

57                 next.nn[i]=now.nn[i]-1;

58             }

59             if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){

60                 vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;

61                 q.push( next );

62             }

63         }

64         char tmp;

65         for( int i=1;i<4;i++ ){

66             strcpy( next.nn,now.nn );//next.nn=now.nn;

67             tmp=now.nn[i];

68             next.nn[i]=now.nn[i-1];

69             next.nn[i-1]=tmp;

70             if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){

71                 vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;

72                 q.push( next );

73             }

74         }

75     }

76     return -1;

77 }

78 

79 int main(){

80     int ca;

81     scanf("%d",&ca);

82     while( ca-- ){

83         scanf("%s%s",a,b);

84         int ans=bfs();

85         printf("%d\n",ans);

86     }

87     return 0;

88 }