leetcode_017 Letter Combinations of a Phone Number

Posted

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了leetcode_017 Letter Combinations of a Phone Number相关的知识,希望对你有一定的参考价值。

Given a digit string, return all possible letter combinations that the number could represent.

A mapping of digit to letters (just like on the telephone buttons) is given below.

技术分享

Input:Digit string "23"
Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].



直接解法:
Python实现
import copy
class Solution:
    # @param {string} digits A digital string
    # @return {string[]} all posible letter combinations
    def letterCombinations(self, digits):
        chr = ["", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"]
        res = []
        for i in range(0, len(digits)):
            num = int(digits[i])
            tmp = []
            for j in range(0, len(chr[num])):
                if len(res):
                    for k in range(0, len(res)):
                        tmp.append(res[k] + chr[num][j])
                else:
                    tmp.append(chr[num][j])
            res = copy.copy(tmp)
        return res

 

dfs方法:还没有看

class Solution:
    # @return a list of strings, [s1, s2]
    def letterCombinations(self, digits):
        def dfs(num, string, res):
            if num == length:
                res.append(string)
                return
            for letter in dict[digits[num]]:
                    dfs(num+1, string+letter, res)
        
        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]
                }
        res = []
        length = len(digits)
        if length == 0:
            return res
        dfs(0, ‘‘, res)
        return res

 





以上是关于leetcode_017 Letter Combinations of a Phone Number的主要内容,如果未能解决你的问题,请参考以下文章

40.leetcode17_letter_combinations_of_a_phone_number

leetcode 17 Letter Combinations of a Phone Number

LeetCode刷题--点滴记录017

LeetCode题828 —— Unique Letter String

leetcode 1079. Letter Tile Possibilities

leetcode1079. Letter Tile Possibilities