LeetCode(Search in Rotated Sorted Array)

タイトルの要件:
Suppose a sorted array is rotated at some pivot unknown to you beforehand.
(i.e.,  0 1 2 4 5 6 7  might become  4 5 6 7 0 1 2 ).
You are given a target value to search. If found in the array return its index, otherwise return -1.
You may assume no duplicate exists in the array. コード:

class Solution {
public:
     int search(int A[], int n, int target) {
    if(A == NULL || n < 0)
      return -1;
    return Search(A, 0, n - 1, target);
  }
  
  int Search(int A[], int start, int end, int target)//       
  {
    if(start > end)
      return -1;
    while(start <= end)
    {
      int mid = start + ((end - start) >> 1);
      if(A[mid] == target)
        return mid;
      else if(A[mid] >= A[start])
      {
        if(target >= A[start] && target < A[mid])
          end = mid - 1;
        else 
          start = mid + 1;
      }
      else 
      {
        if(target <= A[end] && target > A[mid])
          start = mid + 1;
        else 
          end = mid - 1;
      }
    }
    return -1;
  }
};