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Alien Dictionary - Verification

Problem Statement​

In an alien language, surprisingly, they also use English lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters.

Given a sequence of words written in the alien language, and the order of the alphabet, return true if and only if the given words are sorted lexicographically in this alien language.

LeetCode link

Example 1:​

Input: words = ["hello","leetcode"], order = "hlabcdefgijkmnopqrstuvwxyz"

Output: true
Explanation:​

As 'h' comes before 'l' in this language, then the sequence is sorted.

Example 2:​

Input: words = ["word","world","row"], order = "worldabcefghijkmnpqstuvxyz"

Output: false
Explanation:​

As 'd' comes after 'l' in this language, then words[0] > words[1], hence the sequence is unsorted.

Example 3:​

Input: words = ["apple","app"], order = "abcdefghijklmnopqrstuvwxyz"
Output: false

Constraints:​

  • 1 <= words.length <= 100
  • 1 <= words[i].length <= 20
  • order.length == 26
  • All characters in words[i] and order are English lowercase letters.

Code​

Python Code
class Solution:
    def isAlienSorted(self, words: List[str], order: str) -> bool:
        order_map = {}
        for index, val in enumerate(order):
            order_map[val] = index

        for i in range(len(words) - 1):

            for j in range(len(words[i])):
                # If we do not find a mismatch letter between words[i] and words[i + 1],
                # we need to examine the case when words are like ("apple", "app").
                if j >= len(words[i + 1]): return False

                if words[i][j] != words[i + 1][j]:
                    if order_map[words[i][j]] > order_map[words[i + 1][j]]: return False
                    # if we find the first different character and they are sorted,
                    # then there's no need to check remaining letters
                    break

        return True