二分查找

    public  int test(int[] arry,int key){
        int low=0;
        int high=arry.length-1;
        while(low<=high){
            int mid=(high+low)/2;
            if(arry[mid]<key){
                low=mid+1;
            }
            else if(arry[mid]>key){
                high=mid-1;
            }
            else
                return mid;
        }
        return -1;
    }