LeetCode Find Minimum in Rotated Sorted Array系列

#153 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.

#154 Find Minimum in Rotated Sorted Array II

Follow up for "Find Minimum in Rotated Sorted Array":
What if duplicates are allowed?

Would this affect the run-time complexity? How and why? 

显然两道题有着同一个简单的解法：

class Solution {public:    int findMin(vector<int>& nums) {        for(int i = 1; i < nums.size(); i++)            if(nums[i -1] > nums[i]) return nums[i];        return nums[0];    }};

当然这样效率较低，没有充分利用数组已排好序的信息，下面分别是两道题的二分查找解法:

#153 Find Minimum in Rotated Sorted Array

class Solution { public:     int findMin(vector<int>& nums) {         int left = 0, right = nums.size() - 1;         while(left < right){             int mid = (left + right) >> 1;             if(nums[mid] > nums[right])  left = mid + 1;             else right = mid;         }         return nums[left];     } };

#154 Find Minimum in Rotated Sorted Array II

class Solution { public:     int findMin(vector<int>& nums) {         int left = 0, right = nums.size() - 1;         while(left < right){             int mid = (left + right) >> 1;             if(nums[mid] > nums[right])  left = mid + 1;             else right = mid;         }         return nums[left];     } };