Find Minimum in Rotated Sorted Array 

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).

Find the minimum element.

You may assume no duplicate exists in the array.

https://oj.leetcode.com/problems/find-minimum-in-rotated-sorted-array/