离散数学-集合的交并差集运算--STL-set类

代码其实很简单，我们只需要知道set类的使用方法就可以了，比如迭代器的定义（ set<T>::iterator it=a.begin() ），和简单的insert函数插入，以及find函数找到时返回对应的迭代器，找不到时返回该set的end。

#include <iostream>
#include <set>
#define T int
using namespace std;

void ShowSet(set<T> V)
{
	set<T>::iterator it=V.begin();
	for (;it!=V.end();it++) {
		cout<<*it<<" ";
	}
	cout<<endl;
}

void inte(set<T>a,set<T>b)
{
	set<T>::iterator it=a.begin();
	for (;it!=a.end();it++) {
		if (b.find(*it)!=b.end()) {
			cout<<*it<<" ";
		}
	}
	cout<<endl;
}

void Sub(set<T>a,set<T>b)
{
	set<T>::iterator it=a.begin();
	for (;it!=a.end();it++) {
		if (b.find(*it)!=b.end())
			continue;
		cout<<*it<<" ";
	}
	cout<<endl;
}

void unio(set<T>a,set<T>b,set<T>c)
{
	set<T>::iterator it=a.begin();
	for (;it!=a.end();it++) {
		c.insert(*it);
	}
	it=b.begin();
	for (;it!=b.end();it++) {
		c.insert(*it);
	}
	ShowSet(c);
}

int main()
{
	set<T> a,b,c;
	T em;
//	while (cin>>ch&&ch!='0')
//	{
//		a.insert(ch-'0');
//	}
//	ShowSet(a);
	int num1,num2;
	cout<<"Please enter the number of the sets A and B."<<endl;
	cin>>num1>>num2;
	while (num1--) {
		cin>>em;
		a.insert(em);
	}
	while (num2--) {
		cin>>em;
		b.insert(em);
	}
	cout<<"Please enter the operation to be performed.I stands for intersection."<<endl
	<<"U stands for union.S is the different set."<<endl;
	char ch;
	while (cin>>ch) {
		if (ch=='I') {
			inte(a,b);
		}
		else if (ch=='U') {
			unio(a,b,c);
		}
		else if (ch=='S') {
			bool is;
			cout<<"Which one do you want to execute? A - B is true , B - A is false."<<endl;
			cin>>is;
			if (is==1)
				Sub(a,b);
			else
				Sub(b,a);
		}
		else
			cout<<"Input error!"<<endl;
	}
	return 0;
}
/*测试数据：
5 5
1 2 3 4 5
1 2 7 8 9
I
U
S
1
S
0
*/