class Solution: def letterCombinations(self, digits): """ :type digits: str :rtype: List[str] """ # 以字典形式存储号码与字母 d_dict = {'2': ['a','b','c'], '3':['d','e','f'], '4':['g','h','i'], '5':['j','k','l'], '6':['m','n','o'], '7':['p','q','r','s'], '8':['t','u','v'], '9':['w','x','y','z'], } # 组合 ret = list() if len(digits) < 1: return ret # if len(digits) == 1 ret = [i for i in d_dict[digits[0]]] # if len(digits) > 1 for i in digits[1:]: ret = [ m+n for m in ret for n in d_dict[i] ] return ret