https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/
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.
注意，我们要找的最小值，只会在右端，所以如果已经在右端，则挪RIGHT
如果在左端，则挪LEFT 往右端的深沟走
time: o(logn) space: o(1)
1 public int findMin(int[] nums) {
2 if (nums ==null || nums.length ==0) return -1 ;
3 int left = 0, right = nums.length -1;
4 while(left + 1 < right){
5 int mid = left + (right - left)/2 ;
6 if (nums[mid] < nums[right]){
7 right = mid ;
8 } else{
9 //first half: left = mid, move to right
10 left = mid ;
11 }
12 }
13 return nums[left]<nums[right]? nums[left] : nums[right] ;
14 }
