java二分查找

package com.alo.offer;
/**
* 非递归的二分查找
* 适用于已经排序好的数组进行查找
* @author Administrator
*
*/
public class BinarySearch{
public static void main(String[] args) {
int []a= {1,5,9,17,56,89,123,257,368,489,578,684,784,857,942};
System.out.println(new BinarySearch().searchNoRecur(a, 9));
System.out.println(new BinarySearch().search(a, 9, 0, a.length-1));
}
public int searchNoRecur(int []a,int x) {
int low=0,high=a.length-1;
int mid=0;
while(low<=high) {
mid=low+(high-low)/2;
if(x==a[mid]) {
return mid;
}else if(x>a[mid]){
low=mid+1;
}else {
high=mid-1;
}

}
return -1;
}
public int search(int []a,int x,int low ,int high) {
if(low>high) return -1;
int mid =low+(high-low)/2;
if(a[mid]==x) {
return mid;
}else if(x>a[mid]){
return search(a,x,mid+1,high);
}else {
return search(a,x,low,mid-1 );
}
}
}