C++ set 多级排序多维度排序

心已赠人 2022-09-12 06:51 129阅读 0赞

#include <iostream>
    #include <set>
    #include <algorithm>
    using namespace std;
    
    /*Student结构体*/
    struct Student {
    	string	name;
    	int	id;
    	int	score;
    };
    
    /*“仿函数"。为Student set指定排序准则*/
    class studentSortCriterion {
    public:
    	/*类型要与set容器类型一致*/
    	bool operator()( const Student *a, const Student *b ) const
    	{
    		// 成绩相等，按照id从小到大排；成绩不相等，按照成绩从大到小排
    		return( (a->score == b->score) ? (a->id < b->id) : (a->score > b->score) );
    	}
    };
    
    
    int main()
    {
    	set<Student*, studentSortCriterion>	stuSet;
    	set<Student*>	stus;
    
    	Student stu1, stu2, stu3;
    	stu1.name	= "张三";
    	stu1.id		= 1;
    	stu1.score	= 100;
    
    	stu2.name	= "李四";
    	stu2.id		= 2;
    	stu2.score	= 90;
    
    	stu3.name	= "小明";
    	stu3.id		= 3;
    	stu3.score	= 100;
    
    	stuSet.insert( &stu1 );
    	stuSet.insert( &stu2 );
    	stuSet.insert( &stu3 );
    
    	/* 查找 */
    	Student stuTem;
    	stuTem.score	= 100;
    	stuTem.id	= 3;
    	Student						* stuTempPtr;
    	set<Student*, studentSortCriterion>::iterator	iter;
    	iter = stuSet.find( &stuTem );
    	if ( iter != stuSet.end() )
    	{
    		cout << (*iter)->name << endl;
    	}
    
    	else {
    		cout << "Cannot find the student!" << endl;
    	}
    
    
    	/* 遍历 */
    	for ( std::set<Student*, studentSortCriterion>::iterator it = stuSet.begin(); it != stuSet.end(); it++ )
    	{
    		std::cout << (*it)->name << endl;
    	}
    }

上面程序会根据学生ID先进行排名然后再根据分数进行排名，排序准则需要满足以下要求，摘自C++标准库第二版：

![31d9b4a86e9319ece10f6d982e9cfc00.png][]

输出结果：

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA6L2v5Lu25bel56iL5bCP5pa95ZCM5a2m_size_9_color_FFFFFF_t_70_g_se_x_16][]

[c++ set容器排序准则 - 每天一点积累 - 博客园][c_ set_ - _ -]

[31d9b4a86e9319ece10f6d982e9cfc00.png]: /images/20220828/ea7e197658bc4a4083c4c4e6dbe0a090.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA6L2v5Lu25bel56iL5bCP5pa95ZCM5a2m_size_9_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/faed65ae6e2049ee9cbc6d72f3cbfd1d.png
[c_ set_ - _ -]: https://www.cnblogs.com/hong2016/p/6700146.html