LeetCode(162) Find Peak Element

[code]class Solution {
public:
    int findPeakElement(vector<int>& nums) {

        int length = nums.size();

        vector<int> tmp(length + 1, 0);
        tmp[0] = 1;
        tmp[length] = -1;
        for(int i = 1; i < length; i++) {

            if(nums[i] > nums[i - 1])

                tmp[i] = 1;

            else

                tmp[i] = -1;

        }

        for(int i = 0; i < length; i++) {

            if(tmp[i] > 0 && tmp[i + 1] < 0) 

                return i;

        }

    }
};