leetcode—153. Find Minimum in Rotated Sorted Array 在翻转数组寻找最小值

问题描述：

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.

解题思路：

题意就是给定一个排序的数组，按照某个轴翻转，就是后面的移到前面。注意这一题规定数组中没有重复元素，因此可以用二分查找。我们取最后一个元素为检验值，二分查找，若大于它，就取右边，小于取左边，问题求解。时间复杂度O（lgN）.

class Solution {
public:
int findMin(vector<int>& nums) {
int s = 0, t = nums.size()-1, k = nums[t];
//if nums[s] < k return nums[s];
while(s<t){
int mid = (s+t)/2;
if(nums[mid] > k) s = mid+1;
else t = mid;
}
return nums[t];
}
};