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Problem: Verifying an Alien Dictionary

Medium
30 min
Explore how to determine if a list of words is sorted according to a custom alien alphabet order. Learn to apply topological sorting concepts to resolve ordering constraints and develop an algorithm that returns whether the words follow the specified lexicographical sequence.

Statement

In an alien language, the alphabet consists of the same lowercase English letters but arranged in a different order.

Given a list of words, words, written in this alien language, and a string order representing the order of the alien alphabet (as a permutation of lowercase letters), return TRUE if the words are sorted lexicographically according to order; otherwise, return FALSE.

Note: A word a is considered lexicographically smaller than word b if:

  • At the first position where the two words differ, the character in a comes before the character in b in the given order string.

  • If one word is a prefix of the other (and all compared characters are the same), then the shorter word is considered smaller.

Constraints:

  • 11 \leq words.length 103\leq 10^3
  • 11 \leq words[i].length 20\leq 20
  • order.length ==26== 26
  • All the characters in words[i] and order are lowercase English letters.
Problem
Ask
Submissions

Problem: Verifying an Alien Dictionary

Medium
30 min
Explore how to determine if a list of words is sorted according to a custom alien alphabet order. Learn to apply topological sorting concepts to resolve ordering constraints and develop an algorithm that returns whether the words follow the specified lexicographical sequence.

Statement

In an alien language, the alphabet consists of the same lowercase English letters but arranged in a different order.

Given a list of words, words, written in this alien language, and a string order representing the order of the alien alphabet (as a permutation of lowercase letters), return TRUE if the words are sorted lexicographically according to order; otherwise, return FALSE.

Note: A word a is considered lexicographically smaller than word b if:

  • At the first position where the two words differ, the character in a comes before the character in b in the given order string.

  • If one word is a prefix of the other (and all compared characters are the same), then the shorter word is considered smaller.

Constraints:

  • 11 \leq words.length 103\leq 10^3
  • 11 \leq words[i].length 20\leq 20
  • order.length ==26== 26
  • All the characters in words[i] and order are lowercase English letters.