【C++】常用集合算法

0.前言

1.set_intersection

#include 
using namespace std;


// 常用集合算法 交集set_intersection
#include
#include

void myPrint(int val)
{
	cout << val << " ";
}

void test01()
{
	vector<int>v1, v2;

	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
		v2.push_back(i + 5);
	}

	vector<int>TargetV;
	TargetV.resize(min(v1.size(), v2.size()));

	vector<int>::iterator Itend = set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), TargetV.begin());

	for_each(TargetV.begin(), Itend, myPrint);
	cout << endl;
}

int main()
{
	test01();
	cout << "------------------------" << endl;
	//test02();
	//cout << "------------------------" << endl << endl;
	//test03();

	//**************************************
	system("pause");
	return 0;
} 
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2.set_union

#include 
using namespace std;


// 常用集合算法 并集set_union
#include
#include

void myPrint(int val)
{
	cout << val << " ";
}

void test01()
{
	vector<int>v1, v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
		v2.push_back(i + 5);
	}

	vector<int>TargetV;
	//目标容器提前开辟空间
	//最特殊情况 两个容器没有交集， 并集就是两个容器size相加
	TargetV.resize(v1.size() + v2.size());

	vector<int>::iterator itEnd = set_union(v1.begin(), v1.end(), v2.begin(), v2.end(), TargetV.begin());

	for_each(TargetV.begin(), itEnd, myPrint);
	cout << endl;
}

int main()
{
	test01();
	cout << "------------------------" << endl;
	//test02();
	//cout << "------------------------" << endl << endl;
	//test03();

	//**************************************
	system("pause");
	return 0;
} 
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3.set_difference

#include 
using namespace std;


// 常用集合算法 差集set_difference
#include
#include

void myPrint(int val)
{
	cout << val << " ";
}

void test01()
{
	vector<int>v1, v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
		v2.push_back(i + 5);
	}

	vector<int>TargetV;
	//给目标容器开辟空间
	//最特殊情况 两个容器没有交集 取两个容器中大的size作为目标容器开辟空间
	TargetV.resize(max(v1.size(), v2.size()));

	vector<int>::iterator itEnd = set_difference(v2.begin(), v2.end(), v1.begin(), v1.end(), TargetV.begin());
	
	cout << "v2和v1的差集：" << endl;
	set_difference(v2.begin(), v2.end(), v1.begin(), v1.end(), TargetV.begin());
	for_each(TargetV.begin(), itEnd, myPrint);
	cout << endl;

	cout << "v1和v2的差集：" << endl;
	set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), TargetV.begin());
	for_each(TargetV.begin(), itEnd, myPrint);
	cout << endl;
}

int main()
{
	test01();
	cout << "------------------------" << endl;
	//test02();
	//cout << "------------------------" << endl << endl;
	//test03();

	//**************************************
	system("pause");
	return 0;
} 
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