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]).
Find the minimum element.
You may assume no duplicate exists in the array.
Example 1: Input: [3,4,5,1,2] Output: 1 Example 2: Input: [4,5,6,7,0,1,2] Output: 0