LeetCode-162-Find Peak Element

算法描述：

A peak element is an element that is greater than its neighbors.

Given an input array nums, where nums[i] ≠ nums[i+1], find a peak element and return its index.

The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.

You may imagine that nums[-1] = nums[n] = -∞.

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.

Note:

Your solution should be in logarithmic complexity.

解题思路：如果当前元素小于前一个元素，则前一个元素应当为峰值，否则继续向后遍历。

    int findPeakElement(vector<int>& nums) {
        if(nums.size() < 2) return 0;
        for(int i=1; i < nums.size(); i++){
            if(nums[i] < nums[i-1]) return i-1;
        }
        return nums.size()-1;
    }