Okay, let’s take this one step further. Rather than generating just phone words, let’s actually generate phone words. Someone has provided a list of words in English as a package, so we’ll add a filter to add that to our comprehension:
from english_words import english_words_set
def letterCombinations(self, digits: str) -> List[str]:
if not digits:
return []
letters = {
'1': '',
'2': 'abc',
'3': 'def',
'4': 'ghi',
'5': 'jkl',
'6': 'mno',
'7': 'pqrs',
'8': 'tuv',
'9': 'wxyz',
'0': ' ',
}
return [
word
for product in itertools.product(*[
letters[digit] for digit in digits
])
if ((word := ''.join(product)) in english_word_set)
]
I think I like the Walrus/assignment operator (:=), but it still is a bit bizarre at times. Basically, what it does is assign a call to a value (word = ''.join(product) in this case), but also returns it and can be used as an expression, which = cannot. So we can immediately check if it is in english_words. Since that’s a set, it should be pretty fast.
Let’s try it:
>>> letterCombinations('2665')
['amok', 'book', 'cook', 'cool']
>>> letterCombinations('43556')
['hello']
>>> letterCombinations('96753')
['world']
Fun! Not bad for a line more.