Leetcode: letter combinations for phone numbers

@author: Zzq
@software: Pycharm
@file: lettercombinations.py
@time: 2018/10/18 18:33
Requirement: Given a string containing only the number 2-9, returns all combinations of letters that it can represent.
The mapping of numbers to letters is given below (same as the phone keys). Note that 1 does not correspond to any letters.
2:ABC; 3:def; 4:ghi; 5:JKL; 6:mno; 7:PQRS; 8:TUV; 9:wxyz
Input: "23"
Output: ["ad", "AE", "AF", "BD", "Be", "BF", "CD", "CE", "CF"].
IDEA: First the letters represented by every number, and then 22 merge and merge. (Record parity)

Class solution (): Def __init__ (self): Pass def numtoletter (self, num): Dict = {2: ' abc ',                3: ' Def ', 4: "Ghi", 5: "JKL", 6: "MnO", 7: "Pqrs",        8: "TUV", 9: "WXYZ"} return Dict[num] def combine (self, str1, str2):            Len1 = Len (str1) len2 = Len (str2) combined = [] Temp_str = "For I in Range (LEN1): For j in Range (LEN2): Combined.append (temp_str+str1[i]+str2[j]) Temp_str = ' Return Co        mbined def lettercombinations (self, digits): "" ": Type Digits:str:rtype:list[str]" ""            if digits = = "": return [] length = len (digits) letters = [] for i in range (length): cur_num = Int (digits[i]) Cur_letter = Self.numtoletter (cur_num) letters.append (cur_letter ) If Len (Letters) = = 1:return [letters[0][t] for T in range (len (letters[0])) "While Len (Letters) > 1:cur_ Letters = [] If Len (Letters)% 2:for I in range ((Len (Letters)-1)/2): cur _letters.append (Self.combine (letters[i * 2], Letters[i * 2 + 1])) Cur_letters.append (Letters[len (Letters)-1 ]) Else:for I in range (len (Letters)/2): Cur_letters.append (Self.combine (le    Tters[i * 2], Letters[i * 2 + 1])) letters = Cur_letters return letters[0]if __name__ = = "__main__": Answer = solution () print answer.lettercombinations (' 2 ') # Print Len (answer.lettercombinations (' 2345 '))

Leetcode: Alphabetical combination of phone numbers