map/set增删查改

set基本使用

增删查改

set<int> s;
	s.insert(1);
	s.insert(3);
	s.insert(2);
	s.insert(1);
	s.insert(4);
	set<int>::iterator it = s.begin();
	while (it != s.end())
	{
		cout << *it << " ";
		++it;
	}
	cout << endl;
	set<int> c = s;
	auto pos = c.find(3);
	c.erase(pos);
	for (auto e : c)
	{
		cout << e << " ";
	}

set会自动排序去重，因为底层是搜索树，中序遍历是有序的

map的基本使用

void test_map()
{
	map<int, int> m;
	m.insert(pair<int, int>(1, 1));
	m.insert(pair<int, int>(1, 1));
	m.insert(make_pair(2, 2));
	m.insert(make_pair(3, 3));
	map<int, int>::iterator it = m.begin();
	while (it != m.end())
	{
		cout << it->first << " " << it->second;
		cout << endl;
		++it;
	}
	cout << endl;
	for (auto e : m)
	{
		cout << e.first << " " << e.second;
		cout << endl;
	}

}

////计数
void test_map3()
{
	map<string, int> m;
	string str[] = { "西瓜", "西瓜", "西瓜", "香蕉", "草莓", "草莓", "西瓜", "西瓜", "西瓜", "西瓜", };
	//map<string, int> m;
	/*for (auto e : str)
	{
		//map<string, int> m;
		map<string, int>::iterator  it = m.find(e);
		if (it != m.end())
		{
			it->second++;
		}
		else
		{
			m.insert(make_pair(e, 1));
		}
	}*/
	for (auto e : str)
	{
		m[e]++;
	}
	for (auto e : m)
	{
		cout << e.first << " " << e.second << endl;
	}
}

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