1099 字串变换 2002年NOIP全国联赛提高组

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<queue>
 4 #include<cstring>
 5 #include<cstdlib>
 6 #include<map>
 7 using namespace std;
 8 string a,b;
 9 struct node
10 {
11     string x;
12     string y;
13 }bc[9];
14 int num=1;
15 int step=0;
16 map<string,int>bushu;
17 string pc;// 
18 int vis[101];
19 void bfs()
20 {
21     queue<string>q;
22     q.push(a);
23     bushu[q.front()]=0;
24     
25     while(q.size()!=0)
26     {
27         int numm=q.size();
28         string p=q.front();
29         if(p==b)
30                 {
31                 printf("%d",bushu[p]);
32                 exit(0);
33                 }
34         pc=pc+" "+p+" ";
35         q.pop();
36         for(int i=1;i<=num;i++)
37         {
38             string dd=p;
39             string change=p;
40             while(1)
41             {
42                 int where=change.find(bc[i].x);
43                 if(where!=-1&&vis[where]==0)
44                 {
45                     vis[where]=1;
46                     change[where]='*';
47                     
48                     int l=bc[i].x.length();
49                     p.replace(where,l,bc[i].y);
50                     
51                     if(p==b)
52                     {
53                     printf("%d",bushu[dd]+1);
54                     exit(0);
55                     }
56                     
57                     if(pc.find(p)!=-1)continue;// 判重 
58                     pc=pc+" "+p+" ";
59                     
60                     bushu[p]=bushu[dd]+1;
61                     
62                     cout<<step<<" "<<bushu[p]<<" "<<p<<endl;
63                     
64                     if(p==b)
65                     {
66                     printf("%d",bushu[p]);
67                     exit(0);
68                     }
69                     else 
70                     {step++;q.push(p);}
71                     if(bushu[p]>10)
72                     {printf("NO ANSWER!");exit(0);}
73                     p=dd;
74                 }
75                 else break;
76             }
77                 
78         }
79     }
80 }
81 int main()
82 {
83     cin>>a>>b;
84     while(cin>>bc[num].x>>bc[num].y){num++;}
85     bfs();
86     printf("NO ANSWER!");
87     return 0;
88 }