java语言实现二分查找的两种方法

1. 非递归方法
   public static int select(int[] arry,int num){

   int high=arry.length-1;
   int low=0;
   while(low<=high){
   //这种方式取中间值是为了防止溢出
   int mid=low+(high-low)/2;
   if(num<arry[mid]){
       high=mid-1;
   }
   else if(num>arry[mid]){
       low=mid+1;
   }
   else if(num==arry[mid]){
   
   return mid;
   }
   

   }
   return -1;
   }

2. 递归方法
   public static int select1(int [] arry,int low,int high,int num){

   int mid=low+(high-low)/2;
   while(low<=high){
       if(num==arry[mid]){
           return mid;
       }
       else if(num>arry[mid]){
           return select1(arry,mid+1,high,num);
       }
       else if(num<arry[mid]){
           return select1(arry,low,mid-1,num);
       }
   }
   return -1;
   

   }