Decode Ways II LeetCode solution in Python

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# Runtime: 180 ms (Top 97.4%) | Memory: 21.20 MB (Top 53.7%)
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class Solution:
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    def numDecodings(self, s: str):
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        if s[0] == "0":
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            return 0
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        cMap = {
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            "0": 0,
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            "*": 9,
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            "**": 15,
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            "1*": 9,
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            "2*": 6,
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        }  # {char(s) : multiplier} mapping
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        for i in range(1, 27):
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            cMap[str(i)] = 1
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        for i in range(0, 7):
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            cMap["*" + str(i)] = 2
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        for i in range(7, 10):
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            cMap["*" + str(i)] = 1
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        dp = [0] * (len(s) + 1)
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        dp[0], dp[-1] = cMap[s[0]], 1
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        for i in range(1, len(s)):
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            dp[i] += (
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                cMap[s[i]] * dp[i - 1] + cMap.get(s[i - 1 : i + 1], 0) * dp[i - 2]
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            ) % (10**9 + 7)
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            if not dp[i]:
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                return 0
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        return dp[-2]