折半
public class MidSearch {
public static void main(String[] args)
{
int a[]={1,4,6,9,12};
int i=search(a,0,a.length-1,6);
System.out.println(i);
}
public static int search(int a[],int low,int high,int key)
{
int mid=(low+high)/2;
if (a[mid]==key)
return mid;
else if (a[mid]>key)
return search(a,0,mid-1,key);
else
return search(a,mid+1,high,key);
}
}