package com.example.algorithmdemo.sortingAlgorithm;

/**
 * 選擇排序
 */
public class SelectionSort {

    /**
     * 數(shù)組排序
     * @param a
     */
    public static void sort(Comparable[] a){
        for(int i = 0;i<a.length-1;i++){
            //假設(shè)本次遍歷，最小值的索引為i
            int minIndex = i;
            for(int j = i + 1;j < a.length;j++){
                if(greater(a[minIndex],a[j])){
                    //更換最小值索引
                    minIndex = j;
                }
            }
            //交換i索引和minIndex索引的值
            exchange(a,i,minIndex);
        }
    }

    /**
     * 判斷參數(shù)a是否比參數(shù)b大
     * 返回true/false
     * @param a
     * @param b
     * @return
     */
    private static boolean greater(Comparable a,Comparable b){
        return a.compareTo(b)>0;
    }

    /**
     * 數(shù)組元素i和j交換位置
     * @param a
     * @param i
     * @param j
     */
    private static void exchange(Comparable[] a,int i,int j){
        Comparable temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }
}

package com.example.algorithmdemo.test;

import com.example.algorithmdemo.sortingAlgorithm.SelectionSort;

import java.util.Arrays;

public class SelectionTest {
    public static void main(String[] args) {
        Integer[] a = {3,2,6,8,1,4,5,7};
        SelectionSort.sort(a);
        System.out.println(Arrays.toString(a));
    }
}