二分法（课后）

import java.util.*;

public class Erfen {

    public static void main(String[] args) {
        int ary[] = new int[10];
        Random a = new Random();
        for (int i = 0; i < ary.length; i++) {
            ary[i] = a.nextInt(30);

        }
        System.out.print("随机的数组 ");
        for (int shuzu : ary) {
            System.out.print(" " + shuzu);
        }

        System.out.println();
        System.out.print("排序后的数组");
        for (int i = 0; i < ary.length - 1; i++) {
            for (int j = 0; j < ary.length - 1 - i; j++) {
                if (ary[j] > ary[j + 1]) {
                    int c = ary[j];
                    ary[j] = ary[j + 1];
                    ary[j + 1] = c;
                }
            }

            if (i == 8) {
                for (int shuzu : ary) {

                    System.out.print(" " + shuzu);
                }
            }
        }

        System.out.print("\n输入一个数 ");
        Scanner shu = new Scanner(System.in);
        int b = shu.nextInt();
        int d = -1;
        int start = 0;
        int end = ary.length - 1;

        while (start <= end) {
            int middle = (start + end) / 2;
            if (b == ary[middle]) {
                d = middle;
                break;
            } else if (b < ary[middle]) {
                end = middle - 1;
            } else if (b > ary[middle]) {
                start = middle + 1;
            }
        }
        if (d == -1) {
            System.out.println("输入的数字不在数组中");
        } 
        else {
            System.out.println("输入的数字在数组中是ary[" + d + "]=" + ary[d]);
        }

    }

}