How do you solve Vowel Spellchecker on LeetCode?

Vowel Spellchecker (LeetCode #966) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: Using hash maps allows for quick lookups, significantly improving efficiency.

What is the brute force solution for Vowel Spellchecker?

The brute force approach for Vowel Spellchecker is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach checks each query against all words in the wordlist. It first looks for an exact match, then checks for case-insensitive matches, and finally tests for vowel replacements. This is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Vowel Spellchecker?

Vowel Spellchecker uses the following concepts: Array, Hash Table, String. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Vowel Spellchecker?

Always clarify the problem requirements and constraints before jumping into coding. Think about edge cases, such as empty queries or wordlists. Explain your thought process clearly while coding to demonstrate your understanding.

What are common mistakes when solving Vowel Spellchecker?

Not considering case sensitivity when checking for matches. Failing to handle vowel replacements correctly.

#966

Vowel Spellchecker

Medium

ArrayHash TableStringHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(n)

💡

Intuition

Time O(n)Space O(n)

The optimal solution uses a hash map for quick lookups and processes the queries in a single pass. By storing the original words in a map with their lowercase versions, we can efficiently check for matches and vowel replacements.

⚙️

Algorithm

3 steps

1Step 1: Create a set from the wordlist for exact matches.
2Step 2: Create a hash map that maps lowercase words to their original case-sensitive versions.
3Step 3: For each query, check for an exact match, then a case-insensitive match, and finally check for vowel replacements using a loop.

solution.py25 lines

1def spellchecker(wordlist, queries):
2    wordset = set(wordlist)
3    lower_wordlist = {word.lower(): word for word in wordlist}
4    vowels = 'aeiou'
5    results = []
6    for query in queries:
7        if query in wordset:
8            results.append(query)
9        elif query.lower() in lower_wordlist:
10            results.append(lower_wordlist[query.lower()])
11        else:
12            found = False
13            for i in range(len(query)):
14                if query[i] in vowels:
15                    for vowel in vowels:
16                        modified_query = query[:i] + vowel + query[i+1:]
17                        if modified_query.lower() in lower_wordlist:
18                            results.append(lower_wordlist[modified_query.lower()])
19                            found = True
20                            break
21                if found:
22                    break
23            if not found:
24                results.append('')
25    return results

ℹ

Complexity note: The optimal solution runs in O(n) time because we process each query in a single pass and use hash maps for quick lookups, making it efficient for large inputs.

1Using hash maps allows for quick lookups, significantly improving efficiency.
2Understanding the precedence of matching rules is crucial for implementing the solution.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.