【HDOJ】2034 -> 人見人愛A-B

題目鏈接：http://acm.hdu.edu.cn/showproblem.php?pid=2034

#include <iostream>
#include <set>
#include <algorithm>
#include <iterator>
using namespace std;

int main(){
	int m,n,x;
	set<int> s;
	while(cin>>m>>n,m||n){
		s.clear();
		while(m--){
			cin>>x;
			s.insert(x);
		}
		while(n--){
			cin>>x;
			s.erase(x);
		}
		if(!s.size()) printf("NULL\n");
		else{
			copy(s.begin(),s.end(),ostream_iterator<int>(cout," "));
			cout<<endl;
		}
	}
	return 0;
}

簡單方法：

#include <iostream>
#include <set>
#include <vector>
#include <algorithm>
#include <iterator>
#include <functional>
using namespace std;

int _tmain(int argc, _TCHAR* argv[]){
	set<int> s1,s2;
	int m,n,x;
	while(cin>>m>>n,m||n){
		s1.clear(); s2.clear();
		while(m--){cin>>x; s1.insert(x);};
		while(n--){cin>>x; s2.insert(x);};
		vector<int> v(s1.begin(),s1.end());
		v.erase(remove_if(v.begin(),v.end(),[s2](int x){return s2.find(x)!=s2.end();}),v.end());
		if(!v.empty()){ copy(v.begin(),v.end(),ostream_iterator<int>(cout," ")); cout<<endl; }
		else cout<<"NULL"<<endl;
	}
	return 0;
}