java实现 二分查找 非递归与递归2种方式

非递归，利用循环package file;import java.util.Scanner;public class Main {public static void search(int[] a,int key){int low=0;int high=a.length-1;int mid;while(low<=high){mid=(low+high)/2;if(a[mid]==key){System.out.println(mid);return;}else if(a[mid]>key){high=mid-1;}else{low=mid+1;}}return;}public static void main(String[] args) {// TODO Auto-generated method stubScanner in=new Scanner(System.in);System.out.println("输入数组长度：");int len=in.nextInt();System.out.println("输入数组：");int[] a=new int[len];for(int i=0;i<len;i++){a[i]=in.nextInt();}System.out.println("输入key：");int key=in.nextInt();search(a,key);}}

递归方法package file;import java.util.Scanner;public class Main {public static int search(int[] a,int key,int start,int end){if(start>end)return -1;int mid=(start+end)/2;if(a[mid]==key){System.out.println(mid);return mid;}else if(a[mid]>key){return search(a,key,start,mid-1);}else{return search(a,key,mid+1,end);}}public static void main(String[] args) {// TODO Auto-generated method stubScanner in=new Scanner(System.in);System.out.println("输入数组长度：");int len=in.nextInt();System.out.println("输入数组：");int[] a=new int[len];for(int i=0;i<len;i++){a[i]=in.nextInt();}System.out.println("输入key：");int key=in.nextInt();System.out.println(search(a,key,0,len-1));}}