lintcode75- Find Peak Element- medium

public class Solution {
    /*
     * @param A: An integers array.
     * @return: return any of peek positions.
     */
    public int findPeak(int[] A) {
        // write your code here
        if (A == null || A.length == 0){
            throw new IllegalArgumentException();
        }

        int start = 0;
        int end = A.length - 1;

        while (start + 1 < end){
            int mid = start + (end - start) / 2;
            if (A[mid + 1] - A[mid] < 0){
                end = mid;
            } else {
                start = mid;
            }
        }

        if (A[start] > A[end]){
            return start;
        }
        return end;
    }
}