选择排序

选择排序的关键思想就是每次从后面未排序的部分选择最“小”值和未排序部分的第一个元素交换，当整个序列都有序的时候排序结束。简易代码实现及测试用例如下：

import java.util.logging.Handler;



public class Selection {



    private static void exch(Comparable[] a, int i, int j) {

        Comparable tmp = a[i];

        a[i] = a[j];

        a[j] = tmp;

    }



    private static boolean less(Comparable a, Comparable b) {

        return (a.compareTo(b) < 0);

    }



    private static void show(Comparable[] a) {

        int N = a.length;

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

            System.out.print(a[i] + " ");

        }

        System.out.println();

    }



    public static boolean isSorted(Comparable[] a) {

        int N = a.length;

        for (int i = 1; i < N; i++) {

            if (less(a[i], a[i - 1]))

                return false;

        }

        return true;

    }



    public static void sort(Comparable[] a) {

        int N = a.length;

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

            int min = i;

            for (int j = i + 1; j < N; j++) {

                if (less(a[j], a[min]))

                    min = j;

            }

            exch(a, i, min);

        }

    }



    public static void main(String[] args) {

        String[] a = StdIn.readAllStrings();

        Selection.sort(a);

        show(a);

    }



}

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