【机考复盘】华为2021.9.1机考复盘第二题

#include <bits/stdc++.h>
using namespace std;

//知识图谱
int main(){
   int n;
   while(cin>>n){    //输入n的关系对
      unordered_map<string,string> hash;    //val是父节点
      unordered_set<string> instance;    //存储instanceof

      string s1,s2,s3;
      for(int i=0;i<n;i++){
         cin>>s1>>s2>>s3;
         if(s2=="instanceOf")
            instance.insert(s1);    //保存子概念
         hash[s1]=s3;               //保存一一对应的关系
      }
      string ss;
      cin>>ss;
      set<string> ret;
      for(auto s:instance){
         string s1=s;
         while(hash.count(s1)){
            if(hash[s1]==ss){
               ret.insert(s);
               break;
            }
            s1=hash[s1];
         }
      }
      if(ret.size()==0){
         cout<<"empty"<<endl;
      }else{
         int i=0;
         for(auto s:ret){
            if(i==0) cout<<s;
            else cout<<" "<<s;
            ++i;
         }
      }
      return 0;
   }
   
}