[leetcode algorithms]題目17

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"].

自己寫的代碼：

利用python的itertools完成笛卡爾積的運算，注意如果輸入為空要返回[]而不是[]。運行時間58 ms

from itertools import productclass Solution: def __init__(self): self.dic = {2: abc, 3: def, 4: ghi, 5: jkl, 6: mno, 7: pqrs, 8: tuv, 9: wxyz} def letterCombinations(self, digits): if digits: combinations = product(*[self.dic[s] for s in digits]) return [.join(x) for x in combinations] else: return []

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