leetcode-面试题46-把数字翻译成字符串

题目描述：

 

 方法一：动态规划 O(N)

class Solution:
    def translateNum(self, num: int) -> int:
        str_num = str(num)
        n = len(str_num)
        dp = [1 for _ in range(n + 1)]
        for i in range(2,n + 1):
            if str_num[i-2] == '1' or (str_num[i-2] == '2' and str_num[i-1] < '6'):
                dp[i] = dp[i -2] + dp[i -1]
            else:
                dp[i] = dp[i -1]
        return dp[n]