标签：its src oss return abc log pos string+ could
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.
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
leetcode_017 Letter Combinations of a Phone Number
标签：its src oss return abc log pos string+ could
原文地址：http://www.cnblogs.com/ytq1016/p/6866126.html
