问题：求数组的任意峰值。两侧都从-∞开始向上递增。
Example 1:
Input: nums = [1,2,3,1]
Output: 2
Explanation: 3 is a peak element and your function should return the index number 2.
Example 2:
Input: nums = [1,2,1,3,5,6,4]
Output: 1 or 5
Explanation: Your function can return either index number 1 where the peak element is 2,
or index number 5 where the peak element is 6.
方法：二分查找
low=0，high=end
mid=low和high的中值
如果mid<mid+1，则要求目标在mid+1～high
如果mid>mid+1，则要求目标在low～mid
代码参考：
1 class Solution { 2 public: 3 int findPeakElement(vector<int>& nums) { 4 int low=0, high=nums.size()-1; 5 while(low<high){ 6 int mid=low+(high-low)/2; 7 if(nums[mid]>nums[mid+1]){ 8 high=mid; 9 }else{ 10 low=mid+1; 11 } 12 } 13 return low; 14 } 15 };
原文：https://www.cnblogs.com/habibah-chang/p/12538950.html