162. Find Peak Element

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

Given an input array where num[i] ≠ num[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 num[-1] = num[n] = -∞.

For example, in array [1, 2, 3, 1], 3 is a peak element and your function should return the index number 2.

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思想：很简单的一个逻辑题，注意一下边界的判断就好了

C++ AC代码：时间o(n)

class Solution {
public:
    int findPeakElement(vector<int>& nums) {
        int len = nums.size();
        for(int i=0;i<len;i++){
            //简单的逻辑判断，注意下边界
            if((i==0&&nums[i]>nums[i+1])||(i+1==len&&nums[i]>nums[i-1])||(nums[i]>nums[i-1]&&nums[i]>nums[i+1]))
                return i;
        }
        return 0;
    }
};