LeetCode题解(Offer46)：把数字翻译成字符串(Python)

题目：​​原题链接​​（中等）

标签：数组、动态规划

解法一（动态规划）：

class Solution:
    def translateNum(self, num: int) -> int:
        s = str(num)

        # 定义状态列表
        dp = [0] * (len(s) + 1)
        dp[0] = 1
        dp[1] = 1

        for i in range(1, len(s)):
            if s[i - 1] != "0" and int(s[i - 1:i + 1]) < 26:
                dp[i + 1] = dp[i - 1] + dp[i]
            else:
                dp[i + 1] = dp[i]

        return dp[-1]

解法二（优化解法一）：

class Solution:
    def translateNum(self, num: int) -> int:
        s = str(num)

        # 定义状态列表
        last1, last2 = 1, 1

        for i in range(1, len(s)):
            if s[i - 1] != "0" and int(s[i - 1:i + 1]) < 26:
                last1, last2 = last2, last1 + last2
            else:
                last1, last2 = last2, last2

        return last2