折半查找法

package com.zyf.day24;public class Zheban {public static void main(String[] args) {// TODO Auto-generated method stub        int[] arr = {12,15,17,19,30};        int index = halfSearch(arr,19);        System.out.println(index);}public static int halfSearch(int[] arr,int target){int max = arr.length - 1;int min = 0;int mid = (max+min)/2;while(true){if(target>arr[mid]){min = mid + 1;}else if(target<arr[mid]){max = mid - 1;}else{return mid;}//重新计算中间值mid = (min+max)/2;//找不到if(max<min){return -1;}}}}