There is an integer array which has the following features:

• The numbers in adjacent positions are different.
• A[0] < A[1] && A[A.length - 2] > A[A.length - 1].

We define a position P is a peek if:

A[P] > A[P-1] && A[P] > A[P+1]

Find a peak element in this array. Return the index of the peak.

class Solution {

public:

    /**

     * @param A: An integers array.

     * @return: return any of peek positions.

     */

    int findPeak(vector<int> A) {

        int left = , right = A.size() - ;

        while (left < right) {

            int mid = left + (right - left) / ;

            if (A[mid] < A[mid + ]) left = mid + ;

            else right = mid;

        }

        return right;

    }

};

class Solution {

public:

    /**

     * @param A: An integers array.

     * @return: return any of peek positions.

     */

    int findPeak(vector<int> A) {

        for (int i = ; i < A.size(); ++i) {

            if (A[i] < A[i - ]) return i - ;

        }

        return A.size() - ;

    }

};