1 #include <stdio.h>
 2 #include <string.h>
 3 #include <algorithm>
 4 #include <vector>
 5 #include <queue>
 6 #define inf 999999999
 7 using namespace std;
 8 
 9 
10 int map[27][27];
11 int dis[27];
12 int visited[27];
13 
14 
15 void init()
16 {
17     for(int i=0;i<27;i++)
18     {
19         visited[i]=0;
20         dis[i]=inf;
21         for(int j=0;j<27;j++)
22         map[i][j]=inf;
23     }
24 }
25 
26 
27 void SPFA()
28 {
29     queue<int>Q;
30     int u, v;
31     Q.push(1);
32     visited[1]=1;
33     dis[1]=0;
34     while(!Q.empty())
35     {
36         u=Q.front();
37         Q.pop();
38         visited[u]=0;
39         for(v=0;v<26;v++)
40         {
41             if(map[u][v]!=inf&&dis[v]>dis[u]+map[u][v])
42             {
43                 dis[v]=dis[u]+map[u][v];
44                 if(!visited[v])
45                 {
46                     Q.push(v);
47                     visited[v]=1;
48                 }
49             }
50         }
51     }
52 }
53 main()
54 {
55     char a[1001];
56     while(scanf("%s",a)!=EOF)
57     {
58         init();
59         int n=strlen(a);
60         map[a[0]-‘a‘][a[n-1]-‘a‘]=1;
61         while(scanf("%s",a))
62         {
63             if(strcmp(a,"0")==0) break;
64             int n=strlen(a);
65             map[a[0]-‘a‘][a[n-1]-‘a‘]=1;
66         }
67         SPFA();
68         if(dis[‘m‘-‘a‘]!=inf)
69         printf("Yes.\n");
70         else printf("No.\n");
71     }
72 }

 1 #include <iostream>  
 2 #include <string>  
 3 using namespace std;  
 4 string str;  
 5 int father[30];  
 6 int find(int x)  
 7 {  
 8     if(x!=father[x])  
 9         father[x]=find(father[x]);  
10     return father[x];  
11 }  
12 void mere(int x,int y)  
13 {  
14     x=find(x);  
15     y=find(y);  
16     if(x!=y)  
17         father[y]=x;  
18 }  
19 int main()  
20 {  
21     int i;  
22     while(cin>>str)  
23     {  
24         memset(father,0,sizeof(father));  
25         for(i=0;i<29;i++)  
26             father[i]=i;  
27         int len=str.length();  
28         int x=find(str[0]-‘a‘);  
29         int y=find(str[len-1]-‘a‘);  
30         if(x!=y&&y!=‘b‘-‘a‘)  
31             mere(x,y);  
32         while(cin>>str)  
33         {  
34             if(!str.compare("0"))  
35                 break;  
36             len=str.length();  
37             x=find(str[0]-‘a‘);  
38             y=find(str[len-1]-‘a‘);  
39             if(x!=y&&y!=‘b‘-‘a‘)  
40                 mere(x,y);  
41         }  
42         x=find(‘m‘-‘a‘);  
43         y=father[‘b‘-‘a‘];  
44         if(x!=y)  
45             cout<<"No."<<endl;  
46         else  
47             cout<<"Yes."<<endl;  
48     }  
49     return 0;  
50 }