953. Verifying an Alien Dictionary

class Solution:
    def isAlienSorted(self, words: List[str], order: str) -> bool:
        ordering = {letter: i for i, letter in enumerate(order)}
        words = [[ordering[letter] for letter in word] for word in words]
        return all(word1 <= word2 for word1, word2 in zip(words, words[1:]))
        
# less efficient solution        
#     def isAlienSorted(self, words: List[str], order: str) -> bool:
#         if not words:
#             return false

#         for i in range(1, len(words)):
#             # compare each pair of words
#             # if you encounter an out of order pair, return early
#             if not self.alien_ordered(words[i - 1], words[i], order):
#                 return False
            
#         return True
    
#     def alien_ordered(self, first: str, second: str, order: str) -> bool:
#         first_word = list(first)
#         second_word = list(second)
        
#         while first_word and second_word:
#             first_letter = first_word.pop(0)
#             second_letter = second_word.pop(0)
            
#             if order.index(first_letter) < order.index(second_letter):
#                 return True
#             elif order.index(first_letter) == order.index(second_letter):
#                 continue
#             else:
#                 return False
        
#         if first_word and not second_word:
#             return False
#         else:
#             return True