数据结构与算法之二分查找

二分查找的前提是有序：

public class test {public static void main(String[] args) {int []arr=new int[] {0,1,2,3,4,5,6,7,8,9};int index=binarySearch(arr,8);System.out.println(index);}public static  int binarySearch(int[]arr,int value) {int low=0;int high=arr.length-1;while(low<high) {int middle=(low+high)/2;if(arr[middle]==value) {return middle;}else if(value<arr[middle]) {high =middle-1;}else {low=middle+1;}}return -1;}}