二分查找

package sort;

/**
 * Created by lijie35 on 2020-01-19 1:55 PM .
 */
public class BinarySearch {


    public static void main(
            String[] args) {
        int[] arr = {1, 2, 3, 5, 6, 7,13,15, 17};
        int index = 7;
        System.out.println(BinarySearch.search(arr, index));
    }

    public static int search(int[] arr, int num0) {
        int start = 0;
        int end = arr.length - 1;

        while (start <= end) {
            System.out.println(111);
            //中点位置
            int mid = start + ((end - start) >> 1);
            //小于重点，说明在左边
            if (arr[mid] > num0) {
                end = mid;
                //大于中点，说明在右边
            } else if (arr[mid] < num0) {
                start = mid;
            } else {//等于中点
                return mid;
            }
        }
        return -1;

    }

}

来源：CSDN

作者：javalj_hz

链接：https://blog.csdn.net/l4oli/article/details/104040317