public class d {
    public static void main(String[] args) {
        //二分查找
        int []arr={7,23,79,81,103,127,131,147};
        System.out.print("请输入你要查找的数字：");

        int num=1311;
        System.out.println(Findnum(arr,num));
    }

    public static int Findnum(int[] arr, int num) {
        //定义左指针
        int left= 0;
        //定义右指针
        int right=arr.length-1;

        while (true){
            if(left>right)return -1;
            int a=(left+right)/2;
            if(arr[a]>num) {
                right=a-1;
            }else if (num>arr[a]){
                left=a+1;
            }if(arr[a]==num){
                return a;
            }
        }
    }
}

package Day2.text1;

public class demol {
    int max;
    int left;
    int right;

    public demol() {
    }

    public demol(int max, int left, int right) {
        this.max = max;
        this.left = left;
        this.right = right;
    }
}

package Day2.text1;

public class s {
    public static void main(String[] args) {
        int []arr={16,5,9,12,
                21,18,32,23,
                37,26,45,34,
                50,48,61,52,
                73,66};
        //定义要查找的数
        int num=48;
        System.out.println(Findnum1(arr,num));
    }

    private static int Findnum1(int[] arr, int num) {
        //创建对象
        demol arr1=new demol(16,0,3);
        demol arr2=new demol(32,4,7);
        demol arr3=new demol(45,8,11);
        demol arr4=new demol(61,12,15);
        demol arr5=new demol(73,16,17);
        //将所有对象装进数组
        demol []aa={arr1,arr2,arr3,arr4,arr5};
        //遍历查找num属于哪个索引
        for (int i = 0; i < aa.length; i++) {
            if (num<aa[i].max){
                for (int j=aa[i].left;j<=aa[i].right;j++){
                    if(arr[j]==num)return j;
                }
            }
        }
        return -1;
    }

}