二分查找法的递归与非递归

二分查找法的两种实现方式：

    class BinarySearch{
        private int[] array;
        public BinarySearch(int[] array){
            this.array=array;
        }
        //递归方式
        public int searchRecursion(int target){
            if(array!=null){
                return searchRecursion(target,0,array.length-1);
            }
            return -1;
        }
        public int searchRecursion(int target,int start,int end){
            if(start>end){
                return -1;
            }
            int mid=start+(end-start)/2;
            if(array[mid]==target){
                return mid;
            }else if(target<array[mid]){
                return searchRecursion(target,start,mid-1);
            }else{
                return searchRecursion(target,mid+1,end);
            }
        }
        //非递归
        public int search(int target){
            if(array==null){
                return -1;
            }
            int start=0;
            int end=array.length-1;
            while(start<=end){
                int mid=start+(end-start)/2;
                if(array[mid]==target){
                    return mid;
                }else if(target<array[mid]){
                    end=mid-1;
                }else{
                    start=mid+1;
                }
            }
            return -1;
        }
    }