【排序基础】2、使用模板（泛型）编写选择排序算法

使用模板（泛型）编写算法

简单记录-bobo老师的玩转算法系列–玩转算法 -排序基础

操作：添加template

template<typename T>

模板 选择排序算法 代码

02-Selection-Sort-Using-Template main.cpp

#include <iostream>
#include "Student.h"

using namespace std;

template<typename T>
void selectionSort(T arr[], int n){

    for(int i = 0 ; i < n ; i ++){

        int minIndex = i;
        for( int j = i + 1 ; j < n ; j ++ )
            if( arr[j] < arr[minIndex] )
                minIndex = j;

        swap( arr[i] , arr[minIndex] );
    }
}

int main() {

    // 测试模板函数，传入整型数组
    int a[10] = {10,9,8,7,6,5,4,3,2,1};
    selectionSort( a , 10 );
    for( int i = 0 ; i < 10 ; i ++ )
        cout<<a[i]<<" ";
    cout<<endl;

    // 测试模板函数，传入浮点数数组
    float b[4] = {4.4,3.3,2.2,1.1};
    selectionSort(b,4);
    for( int i = 0 ; i < 4 ; i ++ )
        cout<<b[i]<<" ";
    cout<<endl;

    // 测试模板函数，传入字符串数组
    string c[4] = {"D","C","B","A"};
    selectionSort(c,4);
    for( int i = 0 ; i < 4 ; i ++ )
        cout<<c[i]<<" ";
    cout<<endl;

    // 测试模板函数，传入自定义结构体Student数组
    Student d[4] = { {"D",90} , {"C",100} , {"B",95} , {"A",95} };
    selectionSort(d,4);
    for( int i = 0 ; i < 4 ; i ++ )
        cout<<d[i];
    cout<<endl;

    return 0;
}

Student.h

//
// 学生的
//

#ifndef INC_02_SELECTION_SORT_USING_TEMPLATE_STUDENT_H
#define INC_02_SELECTION_SORT_USING_TEMPLATE_STUDENT_H

#include <iostream>
#include <string>

using namespace std;


struct Student{

    string name;
    int score;

    // 重载小于运算法,定义Student之间的比较方式
    // 如果分数相等，则按照名字的字母序排序
    // 如果分数不等，则分数高的靠前
    bool operator<(const Student& otherStudent){
        return score != otherStudent.score ?
               score > otherStudent.score : name < otherStudent.name;
    }

    // 重载<<符号, 定义Student实例的打印输出方式
    friend ostream& operator<<(ostream &os, const Student &student){

        os<<"Student: "<<student.name<<" "<<student.score<<endl;
        return os;
    }
};

#endif //INC_02_SELECTION_SORT_USING_TEMPLATE_STUDENT_H

Java版本

SelectionSort.java

package algo;

import java.util.*;

public class SelectionSort {

    // 我们的算法类不允许产生任何实例
    private SelectionSort(){}

    public static void sort(Comparable[] arr){

        int n = arr.length;
        for( int i = 0 ; i < n ; i ++ ){
            // 寻找[i, n)区间里的最小值的索引
            int minIndex = i;
            for( int j = i + 1 ; j < n ; j ++ )
                // 使用compareTo方法比较两个Comparable对象的大小
                // arr[j].compareTo( arr[minIndex] ) 的结果<0 就是arr[j]小于arr[minIndex]
                if( arr[j].compareTo( arr[minIndex] ) < 0 )
                    minIndex = j;

            swap( arr , i , minIndex);
        }
    }

    private static void swap(Object[] arr, int i, int j) {
        Object t = arr[i];
        arr[i] = arr[j];
        arr[j] = t;
    }

    public static void main(String[] args) {

        // 测试Integer
        Integer[] a = {10,9,8,7,6,5,4,3,2,1};
        SelectionSort.sort(a);
        for( int i = 0 ; i < a.length ; i ++ ){
            System.out.print(a[i]);
            System.out.print(' ');
        }
        System.out.println();

        // 测试Double
        Double[] b = {4.4, 3.3, 2.2, 1.1};
        SelectionSort.sort(b);
        for( int i = 0 ; i < b.length ; i ++ ){
            System.out.print(b[i]);
            System.out.print(' ');
        }
        System.out.println();

        // 测试String
        String[] c = {"D", "C", "B", "A"};
        SelectionSort.sort(c);
        for( int i = 0 ; i < c.length ; i ++ ){
            System.out.print(c[i]);
            System.out.print(' ');
        }
        System.out.println();

        // 测试自定义的类 Student
        Student[] d = new Student[4];
        d[0] = new Student("D",90);
        d[1] = new Student("C",100);
        d[2] = new Student("B",95);
        d[3] = new Student("A",95);
        SelectionSort.sort(d);
        for( int i = 0 ; i < d.length ; i ++ )
            System.out.println(d[i]);
    }
}

Student

package algo;

import java.util.*;

public class Student implements Comparable<Student> {

    private String name;
    private int score;

    public Student(String name, int score){
        this.name = name;
        this.score = score;
    }

    // 定义Student的compareTo函数
    // 如果分数相等，则按照名字的字母序排序
    // 如果分数不等，则分数高的靠前
    @Override
    public int compareTo(Student that) {

        if( this.score < that.score )
            return -1;
        else if( this.score > that.score )
            return 1;
        else // this.score == that.score
            return this.name.compareTo(that.name);
    }

    // 定义Student实例的打印输出方式
    @Override
    public String toString() {
        return "Student: " + this.name + " " + Integer.toString( this.score );
    }
}

Result

D:\Environments\jdk-11.0.2\bin\java.exe -javaagent:D:\Java\ideaIU-2019.2.win\lib\idea_rt.jar=5656:D:\Java\ideaIU-2019.2.win\bin -Dfile.encoding=UTF-8 -classpath D:\IdeaProjects\imooc\Play-with-Algorithms\02-Sorting-Basic\out\production\02-Selection-Sort-Using-Comparable algo.SelectionSort
1 2 3 4 5 6 7 8 9 10 
1.1 2.2 3.3 4.4 
A B C D 
Student: D 90
Student: A 95
Student: B 95
Student: C 100

Process finished with exit code 0