DFS

HDU1181  http://acm.hdu.edu.cn/showproblem.php?pid=1181

 #include<stdio.h>
 #include<algorithm>
 #include<iostream>
 #include<string.h>
 using namespace std;
 struct point{
 char first;
 char last;
 }p[];
 int flag,k;
 char s[];
 char vis[],ma[];
 void dfs(char c){
 if(c=='m'){
     flag=;
     return;
 }
 for(int j=;j<k;j++){
     if(vis[j]==&&p[j].first==c){
             vis[j]=;
         dfs(p[j].last);
     }
 }
 return ;
 }
 int main()
 {
     while(~scanf("%s",&s)){
             if(strcmp(s,"")==)continue;
             p[].first=s[];
             p[].last=s[strlen(s)-];
     k=;
         while(~scanf("%s",&s)&&strcmp(s,"")!=)
         {p[k].first=s[];
     p[k].last=s[strlen(s)-];
     //cout<<p[k].first<<p[k].last<<endl;
     k++;
 
         }
     flag=;
         for(int i=;i<k;i++){
             if(p[i].first=='b'){
                 memset(vis,,sizeof(vis));
                 vis[i]=;
                 dfs('b');
             }
             if(flag==)break;
         }
         if(flag==)
             cout<<"Yes."<<endl;
         else cout<<"No."<<endl;
     }
 }