2025-08-01 14:12:58 +0000 UTC

class Solution:
    def validMountainArray(self, arr: List[int]) -> bool:
        length = len(arr)
        if length < 3:
            return False
        enc_peak = False
        prev = arr[0]
        for i, num in enumerate(arr[1:], 1):
            if num == prev:
                return False
            if not enc_peak and num < prev:
                enc_peak = True
            if enc_peak and (num > prev or i == 1):
                return False   
            prev = num
        return enc_peak