hihoCoder #1062 : 最近公共祖先·一

 1 #include <iostream>
 2 #include <map>
 3 #include <cstdio>
 4 #include <string>
 5 using namespace std;
 6 map<string,string> sontofar;
 7 map<string,int> vis;
 8 
 9 void check(string tmp1,string tmp2)
10 {
11     vis.clear();
12     string ind=tmp1;
13     while( !ind.empty() )
14     {
15         vis[ind]=1;
16         ind=sontofar[ind];        //找不到就是空了
17     }
18 
19     ind=tmp2;
20     while( !ind.empty() && vis[ind]==0 )
21         ind=sontofar[ind];
22 
23     if(ind.empty())
24         cout<<"-1"<<endl;
25     else
26         cout<<ind<<endl;
27 }
28 
29 int main()
30 {
31     //freopen("input.txt","r",stdin);
32     int t, p=0;
33     string tmp1, tmp2;
34 
35     cin>>t;
36     while(t--)
37     {
38         cin>>tmp1>>tmp2;
39         sontofar[tmp2]=tmp1;
40     }
41 
42     cin>>t;
43     while(t--)
44     {
45         cin>>tmp1>>tmp2;
46         check(tmp1,tmp2);
47     }
48     return 0;
49 }