HTMLify

class Solution:
    def letterCombinations(self, digits: str) -> List[str]:
        pad = {
            "2": "abc",
            "3": "def",
            "4": "ghi",
            "5": "jkl",
            "6": "mno",
            "7": "pqrs",
            "8": "tuv",
            "9": "xwyz"
        }
        if not digits:
            return []
        if len(digits) == 1:
            return list(pad[digits])
        combs = []
        d = digits[0]
        loc = self.letterCombinations(digits[1:])
        for l in pad[d]:
            for c in loc:
                combs.append(l + c)
        return combs