941.-valid-mountain-array.md

941. Valid Mountain Array

class Solution:
    def validMountainArray(self, arr: List[int]) -> bool:
        if len(arr) < 3:
            return False
        
        if arr[1] <= arr[0]:return False
        up = True
        for i in range(1,len(arr)):
            if up :
                if arr[i] < arr[i - 1]:
                    up = False
                elif arr[i] > arr[i - 1]: continue
                else: return False                
            else:
                if arr[i] >= arr[i-1]: return False
                
                
        return True and not up