LeetCode [Array]: Find Peak Element

LeetCode [Array]: 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.
You may imagine that num [-1] = num [n] =-∞.
For example, in array [1, 2, 3, 1], 3 is a peak element and your function shocould return the index number 2.
Note:
Your solution shocould be in logarithmic complexity.

This topic requires O (log (N) as the time complexity. binary search can be used, but the update between search zones is not the same here: if the first step of mid is uphill and the next step of mid is downhill, mid is the top of the hill. If the first and last steps of mid are uphill, the top of the hill must be in the second half; if both the first and last steps of the mid are downhill, the top of the hill must be in the first half. In addition, the boundary issue also needs to be handled.

The implementation of my C ++ code is as follows:

int findPeakElement(const vector
 
   &num) {    int low = 0, high = num.size() - 1;    while (low <= high) {        int mid  = (low + high) >> 1;        bool isUphillForward = (mid == 0 ? true : num[mid] > num[mid - 1]);        bool isUphillAfter = (mid == num.size() - 1 ? false : num[mid + 1] > num[mid]);        if (isUphillForward && !isUphillAfter) return mid;        else if (isUphillForward && isUphillAfter) low = mid + 1;        else high = mid - 1;    }    return low;}