数组查找算法之二分法查找

* @date 2020/3/26 - 21:21
 */
public class Thurd {
    public static void main(String[] args) {
        //给定一组数组{1，2，3，4，5，6，7，8，9}，输入目标6所在下标
        int[] arr={1,2,3,4,5,6,7,8,9};
        //目标
        int target = 6;
        //指针
        int index = -1;
        //首
        int begin = 0;
        //尾
        int end = arr.length-1;
        //中间
        int mid = (begin+end)/2;

        while (true){
            if (arr[mid]==target)
            {
                index=mid;
                System.out.println(index);
                break;
            }else{
                if (arr[mid]>target)
                {
                    end=mid-1;
                }else
                {
                    begin=mid+1;
                }
            }
            mid=(begin+end)/2;
        }
    }
}