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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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选择排序