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);
    }

}