[STL训练]2010辽宁省决赛 SPY-题解(C++代码)

//A∩B-C
#include<iostream>
#include<string>
#include<set>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    int a,b,c;
    string name;
    while(cin>>a>>b>>c){
        int cnt=0;
        vector<string>v,vd,ve;
        while(a--){cin>>name;v.push_back(name);}
        set<string>sa(v.begin(),v.end()),sb,sc;
        while(b--){cin>>name;sb.insert(name);}
        while(c--){cin>>name;sc.insert(name);}
        set_intersection(sa.begin(),sa.end(),sb.begin(),sb.end(),back_inserter(vd));
        set<string>sd(vd.begin(),vd.end());
        set_difference(sd.begin(),sd.end(),sc.begin(),sc.end(),back_inserter(ve));
        set<string>se(ve.begin(),ve.end());
        for(int i=0;i<(int)v.size();i++)if(se.count(v[i])){cout<<v[i]<<' ';cnt=1;}
        if(!cnt)cout<<"No enemy spy";
        cout<<endl;
    }
    return 0;
}
//2
#include<iostream>
#include<set>
#include<vector>
using namespace std;
int main()
{
    int a,b,c,cnt;
    string name;
    while(cin>>a>>b>>c){
        cnt=0;
        vector<string>v;
        set<string>mb,mc;
        while(a--){cin>>name;v.push_back(name);}
        while(b--){cin>>name;mb.insert(name);}
        while(c--){cin>>name;mc.insert(name);}
        for(int i=0;i<(int)v.size();i++)
            if(mb.count(v[i])==1&&mc.count(v[i])==0){
                    cout<<v[i]<<' ';
                    cnt=1;
                }
        if(!cnt)cout<<"No enemy spy";
        cout<<endl;
    }
    return 0;
}