Python - Program to Check if a Word is a Lithogram

A lithogram is a word where no letter appears more than once (i.e., all characters are unique).

Python Code:

def is_lithogram(word):

    return len(set(word)) == len(word)  # If all characters are unique, it's a lithogram

# Example Usage

word = "world"

if is_lithogram(word):

    print(f'"{word}" is a lithogram.')

else:

    print(f'"{word}" is NOT a lithogram.')

Explanation:

Convert the Word into a Set (set(word))

A set removes duplicate characters automatically.

Compare Lengths (len(set(word)) == len(word))

If the length of the set is equal to the length of the word, then all characters were unique → It's a lithogram.

Otherwise, some letters repeated → Not a lithogram.

Example Runs:

Example 1:

word = "world"

Set of "world" → {'w', 'o', 'r', 'l', 'd'} (5 unique characters)

Length of set = 5, Length of word = 5

"world" is a lithogram.

Example 2:

word = "hello"

Set of "hello" → {'h', 'e', 'l', 'o'} (4 unique characters)

Length of set = 4, Length of word = 5

"hello" is NOT a lithogram.

Output:

"world" is a lithogram.

"hello" is NOT a lithogram.

Time Complexity:

Converting the word to a set takes O(n),

Checking the length takes O(1).

Total complexity: O(n) (efficient for large words).