C++ sort()与stable_sort()使用指北(附示例代码)

#include <string>
#include <vector>
#include <list>
#include <iostream>
#include <algorithm>//sort

using std::vector;
using std::list;
using std::string;

struct Student
{
    string name;
    double score;
    Student(const string &n, double s) : name(n), score(s) {}
    // 重载 operator< 以按score升序排序(list::sort)
    bool operator<(const Student& other) const {
        return score < other.score;
    }
};

bool CompareByScore(const Student& a, const Student& b) {
    return a.score > b.score; // 降序
}
//
bool CompareStudent(const Student& a, const Student& b) {
    if (a.score != b.score){
        return a.score < b.score;
    }
    return a.name < b.name; // 成绩相同时按名字升序
}

int main(int argc, char *argv[])
{
    std::vector<Student> studentArray = {
        {"Candy", 91.0},
        {"Body", 91.0},
        {"Andy", 91.0},
        {"Lucy", 91.0},
        {"Lily", 90.5},
        {"Luck", 92.5},
        {"Kandy", 95.0},
    };

    do{
        std::cout << "v1: std::sort" << std::endl;
        auto v1 = studentArray;
        std::sort(v1.begin(), v1.end(), [](const Student &a, const Student &b){
            return a.score > b.score;//降序
        });
        for (const auto& s : v1) {
            std::cout << s.name << ": " << s.score << "\n";
        }
    }while(false);


    do{
        // 使用 stable_sort 保证同分学生顺序不变
        std::cout << "\nv2: std::stable_sort" << std::endl;
        auto v2 = studentArray;
        std::stable_sort(v2.begin(), v2.end(), CompareByScore);
        for (const auto& s : v2) {
            std::cout << s.name << ": " << s.score << "\n";
        }
    }while(false);


    do{
        // 对于频繁排序的小型容器，可考虑使用 std::list::sort()（稳定且链表友好）
        std::list<Student> studentList;
        for (const auto& s : studentArray){
            studentList.push_back(s);
        }

        // 使用 std::list::sort() 进行排序
        std::cout << "\nlist1: sort" << std::endl;
        auto list1 = studentList;
        list1.sort();                 // 使用 operator<
        for (const auto& s : list1) {
            std::cout << s.name << ": " << s.score << "\n";
        }

        //使用自定义比较函数
        std::cout << "\nlist2: CompareStudent" << std::endl;
        auto list2 = studentList;
        list2.sort(CompareStudent);
        for (const auto& s : list2) {
            std::cout << s.name << ": " << s.score << "\n";
        }
    }while(false);

    return 0;
}