LeetCode 17 [Letter Combinations of a Phone Number]
原题给一个不包含01的数字字符串,每个数字代表一个字母,请返回其所有可能的字母组合。下图的手机按键图,就表示了每个数字可以代表的字母。样例给定"23"返回["ad","ae","af","bd","be","bf","cd","ce","cf"]解题思路Backtracking,递归求解对于每一个数字可能对应的字母,看做树的一层完整代码classSolution(object):defletter