"""
Efficient algorithm using Python sets:
--------------------------------------
Each word is converted into a set of its unique letters.
Example:
"algebraic" -> {'a', 'l', 'g', 'e', 'b', 'r', 'i', 'c'}
Then:
- Start with the set of letters from the first word.
- Intersect with each subsequent word's letter set.
- The final set contains letters common to all words.
This uses Python's built-in:
- set()
- set.intersection()
- clear, idiomatic functional decomposition
"""
def letters_of(word):
"""Return a set of unique letters in the word."""
return set(word)
def common_letters(words):
"""Return letters that appear in *every* word."""
if not words:
return set()
# Start with letters of the first word
common = letters_of(words[0])
# Intersect with each subsequent word
for word in words[1:]:
common &= letters_of(word)
return common
def print_letters(letters):
"""Print letters in sorted order."""
print(" ".join(sorted(letters)))
def main():
words = [
"algebraic",
"alphabetic",
"ambiance",
"abacus",
"metabolic",
"parabolic",
"playback",
"drawback",
"fabricate",
"flashback",
"syllabic"
]
result = common_letters(words)
print("Common letters across all words:")
print_letters(result)
if __name__ == "__main__":
main()
"""
run:
Common letters across all words:
a b c
"""
