Hi, here's your problem today. This problem was recently asked by Microsoft:
Given an array of heights, determine whether the array forms a "mountain" pattern. A mountain pattern goes up and then down.
class Solution(object): def validMountainArray(self, arr): # Fill this in.
print(Solution().validMountainArray([1, 2, 3, 2, 1]))
print(Solution().validMountainArray([1, 2, 3]))