在c ++中对对象数组进行排序，重复值[重复]

Question

我目前正在尝试对一组对象进行排序。排序函数工作正常，但如果像 age 这样的值重复，我想根据 height 对它们进行排序，如果 height 重复我想按 weight 对它们进行排序。顺序基于用户输入。

我想让程序尽可能快地运行，同时尽可能少地使用内存。这就是我发布这个问题的原因，只是为了确保找到最佳解决方案。

我被困住了。我不知道如何在这个数组中获取重复值并同时在不同条件下对它们进行排序，而不是对所有对象进行排序。

这是代码：

#include <iostream>
using namespace std;

class Person{
public:
    string name;
    int age;
    int weight;
    int height;
};
    
void sortByAge(int n, Person * array);
void sortByHeight(int n, Person * array);
void sortByWeight(int n, Person * array);
    
int main()
{
    int n;
    cin >> n;

    Person * people = new Person[n];

    for(int i = 0; i < n; i++) {
        cin >> people[i].name >> people[i].age >> people[i].weight >> people[i].height;
    }
    cout << endl << endl;

    int firstOrder, secondOrder, thirdOrder;
    cout << "Enter the order of sorting, choose numbers form 1 to 3, where 1 is sorting by Age, 2 is sorting by Height and 3 is sorting by weight \n";
    cin >> firstOrder >> secondOrder >> thirdOrder;

    if(firstOrder == 1) {
        sortByAge(n,people);
        if(secondOrder == 2) {
            sortByHeight(n,people);
            sortByWeight(n,people);
        } else if(secondOrder == 3) {
            sortByWeight(n,people);
            sortByHeight(n,people);
        }
    } else if(firstOrder == 2) {
        sortByHeight(n,people);
        if(secondOrder == 1) {
            sortByAge(n,people);
            sortByWeight(n,people);
        } else if(secondOrder == 3) {
            sortByWeight(n,people);
            sortByAge(n,people);
        }
    } else if(firstOrder == 3) {
        sortByWeight(n,people);
        if(secondOrder == 1) {
            sortByAge(n,people);
            sortByHeight(n,people);
        } else if (secondOrder == 2) {
            sortByHeight(n,people);
            sortByAge(n,people);
        }
    }
    delete [] people;
    return 0;
}

void sortByAge(int n, Person * array) {
    int y = 0;
    Person x;
    for(int i = 1; i < n; i++) {
        x = array[i];
        y = i - 1;
        while(y >= 0 && array[y].age < x.age) {
            array[y+1] = array[y];
            y--;
        }
        array[y+1] = x;
    }
}

void sortByWeight(int n, Person * array) {
    int y = 0;
    Person x;
    for(int i = 1; i < n; i++) {
        x = array[i];
        y = i - 1;
        while(y >= 0 && array[y].weight < x.weight) {
            array[y+1] = array[y];
            y--;
        }
        array[y+1] = x;
    }
}

void sortByHeight(int n, Person * array) {
    int y = 0;
    Person x;
    for(int i = 1; i < n; i++) {
        x = array[i];
        y = i - 1;
        while(y >= 0 && array[y].height < x.height) {
            array[y+1] = array[y];
            y--;
        }
        array[y+1] = x;
    }
}

Answer 1

我建议使用std::tie 来简化多个字段的排序。

例子：

#include <algorithm>
#include <iostream>
#include <string>
#include <tuple>
#include <vector>

class Person{
public:
    std::string name;
    int age;
    int weight;
    int height;
};

// A comparison function taking member pointers as template parameters
// and using std::tie to compare two Persons.
template<auto... S>
bool compfunc(const Person& lhs, const Person& rhs) {
    return std::tie((lhs.*S)...) < std::tie((rhs.*S)...);
}

int main() {
    std::vector<Person> persons {
        {"foo", 10, 10, 10},
        {"foo", 9, 10, 10},
        {"foo", 10, 9, 10},
        {"foo", 10, 10, 9},
        {"bar", 11, 12, 13},
    };

    // Supply the sort order as template parameters where the first parameter
    // has the highest priority.
    std::sort(persons.begin(), persons.end(), compfunc<&Person::name,
                                                       &Person::age,
                                                       &Person::weight,
                                                       &Person::height>);

    for(auto&[n,a,w,h] : persons) {
        std::cout << n << ' ' << a << ' ' << w << ' ' << h << '\n';
    }
}

输出：

bar 11 12 13
foo 9 10 10
foo 10 9 10
foo 10 10 9
foo 10 10 10