Number of Ways to Separate Numbers LeetCode solution in Python

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# Runtime: 11887 ms (Top 6.00%) | Memory: 14.2 MB (Top 88.00%)
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class Solution:
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    def numberOfCombinations(self, num: str) -> int:
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        if num[0] == "0":
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            return 0
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        N = len(num)
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        MOD = int(10**9 + 7)
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        ways = (N + 1) * [0]
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        acc = list(ways)
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        for n in range(1, N + 1):
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            ways[n] = int(n == N or num[n] != "0")
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            for i in range(n + 1, N + 1):
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                if i < N and num[i] == "0":
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                    ways[i] = 0
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                    continue
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                ways[i] = (
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                    acc[i - n]
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                    + (
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                        (w := ways[i - n])
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                        and i >= 2 * n
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                        and num[i - 2 * n : i - n] <= num[i - n : i]
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                        and w
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                    )
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                ) % MOD
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            for i in range(n, N + 1):
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                a = (acc[i] + ways[i]) % MOD
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                acc[i] = a
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        return acc[N]