Suppose an array sorted in ascending order 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.

1. 简单来说像是个二分查找，但是需要找到旋转轴，初步想法是递归，能过

2. 看别的solution 并不需要找轴，可以在二分的基础上直接找，试试看可以