sort使用

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一、简单排序

1.基础

//1.sort顺序排序：默认从小到大排序
#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int num[55] = {0};
    num[0] = 9;
    num[1] = 2;
    num[2] = -5;
    num[3] = 5;
    num[4] = 7;
    num[5] = 22;
    
    //使用sort函数对下标为(0, 5)数字的区间进行排序
    sort(num, num + 6);
    for(int i = 0; i < 6; ++i){
        cout << num[i] << endl;
    }
    cout << endl;
    return 0;
}

2.仿函数

//2.sort逆序排序：利用C++中的greater<int>()函数实现
#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int num[55] = {0};
    num[0] = 9;
    num[1] = 2;
    num[2] = -5;
    num[3] = 5;
    num[4] = 7;
    num[5] = 22;
    
    //重点:利用C++中的greater<int>()函数进行从大到小的排序
    sort(num, num + 6, greater<int>());
    for(int i = 0; i < 6; ++i){
        cout << num[i] << endl;
    }
    cout << edl;
    return 0;
}

3.自定义函数

//3.sort逆序排序：利用自定义比较函数实现
#include <iostream>
#include <algorithm>
using namespace std;

bool cmp(const int &a, const int &b){
	return a > b;//前面的元素值a大于后面的元素值b
}

int main(){
    int num[55] = {0};
    num[0] = 9;
    num[1] = 2;
    num[2] = -5;
    num[3] = 5;
    num[4] = 7;
    num[5] = 22;
    
    //重点:利用自定义的比较函数进行从大到小的排序
    sort(num, num + 6, cmp);
    for(int i = 0; i < 6; ++i){
        cout << num[i] << endl;
    }
    cout << endl;
    return 0;
}

4.自定义类型排序

#include <iostream>
#include <algorithm>
using namespace std;

struct student{
	int num, age, score;
    string name;
};

bool cmp(const student &a, const student &b){
    return a.score > b.score;
}

int main(){
    student stu[205];
    stu[0].name = "Wu"; 
    stu[0].num = 1;
    stu[0].age = 20;
    stu[0].score = 60;
    stu[1].name = "huang";
    stu[1].num = 2;
    stu[1].age = 25;
    stu[1].score = 150;
    stu[2].name = "cui";
    stu[2].num = 3;
    stu[2].age = 15;
    stu[2].score = 50;
    
    //利用cmp函数按照分数score对自定义类型student进行排序
    sort(stu, stu + 3, cmp);
    for(int i = 0; i < 3; ++i){
        cout << stu[i].num << " " << stu[i].name << " " << stu[i].score << endl;
    }
    return 0;
}

二、复杂类型排序

1.自定义函数

当学生分数相同时，按照学号从大到小排序

#include <iostream>
#include <algorithm>
using namespace std;

struct student{
	int num, age, score;
    string name;
};

//如果学生分数相同，则按照学生序号排名
bool cmp(const student &a, const student &b){
    if(a.score == b.score){
        return a.num < b.num;
    }
    return a.score > b.score;
}

int main(){
    student stu[205];
    stu[0].name = "Wu"; 
    stu[0].num = 1;
    stu[0].age = 20;
    stu[0].score = 60;
    stu[1].name = "huang";
    stu[1].num = 2;
    stu[1].age = 25;
    stu[1].score = 150;
    stu[2].name = "cui";
    stu[2].num = 3;
    stu[2].age = 15;
    stu[2].score = 60;
    
    //利用cmp函数按照score对自定义类型student进行排序，如果分数相同则按照学号排序
    sort(stu, stu + 3, cmp);
    for(int i = 0; i < 3; ++i){
        cout << stu[i].num << " " << stu[i].name << " " << stu[i].score << endl;
    }
    return 0;
}

2.重载小于号

#include <iostream>
#include <algorithm>
using namespace std;

struct student{
	int num, age, score;
    string name;
    //使用重載小于号
    bool op
};

//如果学生分数相同，则按照学生序号排名
bool cmp(const student &a, const student &b){
    if(a.score == b.score){
        return a.num < b.num;
    }
    return a.score > b.score;
}

int main(){
    student stu[205];
    stu[0].name = "Wu"; 
    stu[0].num = 1;
    stu[0].age = 20;
    stu[0].score = 60;
    stu[1].name = "huang";
    stu[1].num = 2;
    stu[1].age = 25;
    stu[1].score = 150;
    stu[2].name = "cui";
    stu[2].num = 3;
    stu[2].age = 15;
    stu[2].score = 60;
    
    //利用cmp函数按照score对自定义类型student进行排序，如果分数相同则按照学号排序
    sort(stu, stu + 3);
    for(int i = 0; i < 3; ++i){
        cout << stu[i].num << " " << stu[i].name << " " << stu[i].score << endl;
    }
    return 0;
}