二分查找算法

package offer;

/**
 * 二分查找
 */
public class BinarySearch {

    public static int binarySearch(int[] a ,int v){
        int mid;
        int lo = 0;
        int hi = a.length - 1;

        while (lo <= hi){
            mid = lo + ( (hi - lo) >>> 1 );
            if (a[mid] == v){
                return mid;
            }else if (a[mid] < v){
                lo = mid + 1;
            }else{
                hi = mid - 1;
            }
        }
        return -1;

    }


    public static void main(String[] args){
        int a[] = {1,2,3,4,5,6,7,8,9};
        System.out.println(binarySearch(a,5));
    }

}