题目
基本思路
用递归或者dfs
比如给‘234’吧,先看2,那现在应该是[‘a’,’b’,’c’],
那再加上3呢,是不是在这个[‘a’,’b’,’c’]的基础上,[‘a’,’b’,’c’]每一个的后面分别加上‘d’,’e’,’f’:也就是 [“ad”, “ae”, “af”, “bd”, “be”, “bf”, “cd”, “ce”, “cf”],
然后再加4的’g”h”i’,以此类推。
代码
class Solution:
def letterCombinations(self, digits):
"""
:type digits: str
:rtype: List[str]
"""
if len(digits) == 0:
return []
self.mapList = [' ','1', "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"]
ans = ['']
for digit in digits:
ans = self.combination(int(digit),ans)
return ans
def combination(self,digit,ans):
return [j+i for i in self.mapList[digit] for j in ans]
结果
25 / 25 test cases passed.
Status: Accepted
Runtime: 32 ms