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.
The array may contain duplicates.
思路：有重复元素的时候，不能按I中这么分三类（反例：Input: [3,3,1,3]=>将roate in right判断成没有rotate）。解决方法是，当碰到nums[start]=nums[end]的情况时，end-1，寻找不同元素再进行二分法。
class Solution {
public:
int findMin(vector<int>& nums) {
return dfs(nums,0,nums.size()-1);
}
int dfs(vector<int>& nums, int start, int end){
if(start==end) return nums[start];
if(nums[start]==nums[end]) return dfs(nums,start, end-1);
int mid = start + ((end - start) >> 1);
if(nums[mid] > nums[end]){ //rotate in the right
return dfs(nums, mid+1,end);
}
else if(nums[start] <= nums[mid]){ //no rotate
return nums[start];
}
else{ //rorate in the left
return dfs(nums, start, mid);
}
}
};