1121 Damn Single (25 分)难度: 一般 / 知识点: 哈希表，模拟

Posted 2021-12-18 辉小歌

https://pintia.cn/problem-sets/994805342720868352/problems/994805352359378944

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
unordered_map<string,string>mp;
unordered_map<string,int>hush;
int n,m;
string s[N];
vector<string>ve;
int main(void)

    cin>>n;
    for(int i=0;i<n;i++)
    
        string a,b; cin>>a>>b;
        mp[a]=b,mp[b]=a;
    
    cin>>m;
    for(int i=0;i<m;i++) cin>>s[i],hush[s[i]]++;
    for(int i=0;i<m;i++)
        if(!hush[mp[s[i]]]) ve.push_back(s[i]);
    cout<<ve.size()<<endl;
    sort(ve.begin(),ve.end());
    for(int i=0;i<ve.size();i++) 
    
        if(i) cout<<" ";
        cout<<ve[i];
    
    return 0;