How do you solve Unique Morse Code Words on LeetCode?

Unique Morse Code Words (LeetCode #804) 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 a set allows for efficient tracking of unique transformations.

What is the brute force solution for Unique Morse Code Words?

The brute force approach for Unique Morse Code Words is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves transforming each word into its Morse code representation and then checking how many unique transformations exist. This is straightforward but inefficient for larger inputs. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Unique Morse Code Words?

Unique Morse Code Words uses the following concepts: Array, Hash Table, String. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Unique Morse Code Words?

Clearly explain your thought process and how you arrived at each step. Consider edge cases, such as empty input or single-character words. Practice transforming simple words to Morse code to solidify your understanding.

What are common mistakes when solving Unique Morse Code Words?

Not using a set to store unique transformations, leading to incorrect counts. Overcomplicating the transformation process instead of using direct indexing.

#804

Unique Morse Code Words

Easy

ArrayHash TableStringHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(n)

The optimal approach uses a set to store unique Morse code transformations directly, eliminating the need for nested loops. This reduces time complexity significantly.

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Algorithm

4 steps

1Step 1: Create a Morse code mapping for each letter.
2Step 2: Initialize a set to store unique Morse transformations.
3Step 3: For each word, convert it to Morse code and add the transformation to the set.
4Step 4: Return the size of the set, which represents the number of unique transformations.

solution.py7 lines

1def uniqueMorseRepresentations(words):
2    morse_code = [".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."]
3    transformations = set()
4    for word in words:
5        transformation = ''.join(morse_code[ord(c) - ord('a')] for c in word)
6        transformations.add(transformation)
7    return len(transformations)

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Complexity note: The time complexity is O(n) because we only iterate through the list of words once, and each transformation is computed in constant time. The space complexity is O(n) due to the storage of unique transformations in a set.

1Using a set allows for efficient tracking of unique transformations.
2Understanding Morse code mapping is crucial for the transformation process.

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