数据结构&算法——Java.zip

import java.util.Scanner; /** * Created by 96274 on 2018/11/18. */ public class half { //递归 public static int binarySearch(int t , int left, int right,int a[]){ //System.out.println("left="+left+",right="+right); if(a.length<=0 ||t>a[right] || t< a[left] ){ return -1; } if(left<=right){ int mid = (left+right)/2; if(a[mid] == t) return mid; if(t>a[mid]){ return binarySearch(t,mid+1,right,a); }else{ return binarySearch(t,left,mid-1,a); } } return -1; } //非递归 public static int binarySearch(int t ,int a[]){ int left = 0,right = a.length-1; if(a.length<=0||t>a[right] || t< a[left]){ return -1; } while(left<=right){ int mid = (left+right)/2; if(a[mid] == t) return mid; if(t>a[mid]){ left = mid+1; }else{ right = mid-1; } } return -1; } public static void main(String[] args){ int a[] = {1,2,3,3,5,6,7,8,9,19,20}; int t ; while(true){ Scanner sc = new Scanner(System.in); t = sc.nextInt(); int x = binarySearch(t,a);//binarySearch(t,0,(a.length-1),a); if(x ==-1){ System.out.println("不存在！"); }else { System.out.println("它在数组中的下标为："+x); } } } }