lintcode-medium-Find Peak Element

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)
            return 0;
        
        int left = 1;
        int right = A.length - 2;
        
        while(left < right - 1){
            
            int mid = left + (right - left) / 2;
        
            if(A[left] <= A[mid] && A[mid] <= A[right])
                left = mid;
            else if(A[left] >= A[mid] && A[mid] >= A[right])
                right = mid;
            else if(A[left] <= A[mid] && A[right] >= A[mid])
                right--;
            else
                left++;
            
        }
        
        if(A[left] > A[right])
            return left;
        else
            return right;
    }
}