总结：这个问题可推广到所有排列组合问题上，思想固定一个初始化字符列表，遍历列表中的字符依次累加进去
def callnum(digits): callnumbers={'2':'abc','3':'def','4':'ghi','5':'jkl','6':'mno','7':'pqrs','8':'tuv','9':'wxyz'} output = [key for key in callnumbers[digits[0]]] print(output) for index in range(1, len(digits)): number = digits[index] if number in [0,1]: break options = [] for key in callnumbers[number]: options += [option+key for option in output] print(options) output = options return output callnum(['2','3'])
