class Solution {public:    int findPeakElement(const vector<int> &num) {        int size = num.size();        int left = 0;        int right = size - 1;        while (left <= right) {            int mid = (left + right) / 2;            if ((mid == 0 || num[mid] > num[mid-1]) &&                (mid == size - 1 || num[mid] > num[mid+1])) {                return mid;            }            if (mid != 0 && num[mid] < num[mid-1]) {                right = mid - 1;            } else {                left = mid + 1;            }        }        return -1;    }};