二分法（数组形式）

public class BinarySearch{public static void main(String[]args){int arr[]=new int[]{1,2,3,4,5,6,7,8,9,10};System.out.println(binSearch(arr,10));}public static int  binSearch(int[]arr,int target){int mid;int first=0;int last=arr.length-1;//当last=arr.length-1时循环控制应为first<=lastwhile(first<=last){mid=first+((last-first)>>1);//避免数据溢出if(target==arr[mid]){return mid;}else if(target>arr[mid]){first=mid+1;}else{last=mid-1;//易错点}}return -1;}}