Verifying an Alien Dictionary

When dealing with languages beyond Earth, traditional lexicographical order no longer applies. Instead, verifying an alien dictionary requires a fresh approach that respects the custom alphabet provided. In this guide, we explore dictionary validation under alien language rules, using efficient methods for order verification and string comparison.

Understand the Alien Language Problem

In an alien world, the sequence of letters may differ drastically from English. Hence, character precedence must align with their custom alphabet, not our familiar A-Z. Given a list of words and an alien alphabet, our goal is sequence validation — to check if the words are sorted according to the alien language rules.

Step 1: Alien Alphabet Mapping

To start, we need to create an alien alphabet mapping. This step involves assigning an index to each character based on its position in the alien order. Efficient word sorting depends on this mapping for accurate string comparison later.

Example Mapping

If the alien alphabet is "hlabcdefgijkmnopqrstuvwxyz", then:

• 'h' → 0
• 'l' → 1
• 'a' → 2
• and so on.

This character precedence guide speeds up order verification between words.

Step 2: Word-by-Word String Comparison

Using the mapping, we conduct string comparison for every adjacent pair of words:

• Compare characters one by one.
• At the first difference, check if the first word's character has lower character precedence than the second.
• If not, dictionary validation fails.

If no mismatches are found but the first word is longer, sequence validation also fails (shorter words should come first if prefixes match).

Step 3: Algorithm for Dictionary Validation

Here’s a step-by-step breakdown:

1. Build the alien alphabet mapping.
2. Loop through the word list.
3. Perform string comparison on adjacent words.
4. Validate each word pair according to the custom alphabet.

This ensures proper order verification and identifies violations of the alien language rules.

Python Code Example

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def isAlienSorted(words, order):
    alien_order = {char: idx for idx, char in enumerate(order)}
    
    for i in range(len(words) - 1):
        word1, word2 = words[i], words[i + 1]
        for j in range(min(len(word1), len(word2))):
            if word1[j] != word2[j]:
                if alien_order[word1[j]] > alien_order[word2[j]]:
                    return False
                break
        else:
            if len(word1) > len(word2):
                return False
    return True

This approach is clean, effective, and ensures full dictionary validation based on alien language rules.

Time Complexity and Space Complexity

• Time Complexity: O(N × M), where N is the number of words and M is the average length of words.
• Space Complexity: O(1), assuming the size of the alphabet is fixed.

Efficient order verification and string comparison keep performance optimal even for large datasets.

Common Edge Cases

• Identical words should not fail validation.
• A word being a prefix of another longer word should still maintain correct lexicographical order.
• Empty lists or custom alphabets must be handled gracefully.

Practical Applications

Understanding alien language rules is crucial for broader areas like:

• Customized sorting engines.
• Text processing in fantasy games.
• Internationalization where custom alphabets exist.

In every case, word sorting based on character precedence becomes fundamental.

Conclusion

Verifying an alien dictionary requires careful attention to lexicographical order using a custom alphabet. By building an alien alphabet mapping, performing efficient string comparison, and ensuring strict sequence validation, we can solve this order verification problem cleanly. Whether dealing with Earth-based languages or interstellar ones, mastering dictionary validation strategies sharpens your problem-solving skills for any word sorting challenge.