stl::(11)常用查找算法

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

// find算法查找元素   返回查找元素位置
void find1()
{
	vector<int >v;
	for (int i = 0; i < 10; i++)
	{
		v.push_back(i);
	}
	vector <int >::iterator pos = find(v.begin(), v.end(), 5);   // 查找元素为5的元素
	if (pos!=v.end())
	{
		cout << "找到了。。。" << endl;
	}
	else
	{
		cout << "未找到。。。" << endl;
	}
}


class Person {
public:
	Person(string name,int age) 
	{
		m_age = age;
		m_name = name;
	}
	bool  operator==(const Person &p)const
	{
		if (this->m_name == p.m_name&&this->m_age == p.m_age)
			return true;
		return false;
	}
	string m_name;
	int m_age;
};

// find查找自定义类型
void find2()
{
	vector<Person>v;
	Person p1("a", 11);
	Person p2("b", 22);
	Person p3("c", 33);
	v.push_back(p1);
	v.push_back(p2);
	v.push_back(p3);

	vector <Person>::iterator pos = find(v.begin(), v.end(), p2);   // 查找元素为p2的元素
	if (pos != v.end())
	{
		cout << "找到了:" << (*pos).m_name << (*pos).m_age << endl;
	}
	else
	{
		cout << "未找到。。。" << endl;
	}
}


class  MyCompare :public binary_function<Person*, Person*, bool > {
public:
	bool operator()(const Person * p1,const Person * p2) const
	{
		if (p1->m_name == p2->m_name && p1->m_age == p2->m_age)
		{
			return true;
		}
		return false;
	}
};

void find3()
{
	vector<Person*>v;
	Person p1("a", 11);
	Person p2("b", 22);
	Person p3("c", 33);
	v.push_back(&p1);
	v.push_back(&p2);
	v.push_back(&p3);

	Person *p = new Person("b", 22);

	vector <Person*>::iterator pos = find_if(v.begin(), v.end(), bind2nd(MyCompare(), p));   // 查找元素为p1的元素
	if (pos != v.end())
	{
		cout << "找到了:" << (*pos)->m_name << (*pos)->m_age << endl;
	}
	else
	{
		cout << "未找到。。。" << endl;
	}
}


// adjacent_find算法查找相邻重复元素，   返回相邻元素的第一个位置的迭代器
void find4()
{
	vector<int>v;
	v.push_back(1);
	v.push_back(2);
	v.push_back(3);

	vector<int>::iterator pos = adjacent_find(v.begin(), v.end());
	if (pos != v.end())
	{
		cout << "找到了相邻元素" << endl;
	}
	else
	{
		cout << "未找到相邻。。" << endl;
	}
}

// binary_search算法 二分查找   无序序列中不可用  返回true/false
void find5() 
{
	vector<int >v;
	for (int i=0;i<10;i++)
	{
		v.push_back(i);
	}
	bool ret=binary_search(v.begin(), v.end(), 4);

	if (ret) 
	{
		cout << "找到find5"<<endl;
	}
	else
	{
		cout << "未找到find5"<<endl;
	}
}

// count算法 统计元素出现次数 返回元素个数
void find6()
{
	vector<int >v;
	for (int i = 0; i < 10; i++)
	{
		v.push_back(i);
	}

	int num=count(v.begin(),v.end(),4);
	cout <<"出现次数："<< num<<endl;
}


class ThenFour {

public:
	bool operator()(int v)
	{
		return v > 4;
	}
};

// count_if算法 按条件统计元素出现次数 返回元素个数
void find7()
{
	vector<int >v;
	for (int i = 0; i < 10; i++)
	{
		v.push_back(i);
	}

	int num = count_if(v.begin(), v.end(), ThenFour());
	cout << "出现大于4的次数：" << num << endl;
}

int main()
{
	find1();
	find2();
	find3();
	find4();
	find5();
	find6();
	find7();
}