Combination Sum IV LeetCode solution in Python

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class Solution:
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    def combinationSum4(self, nums: List[int], target: int) -> int:
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        dp = [0] * (target + 1)
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        dp[0] = 1
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        for i in range(1, target + 1):
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            for num in nums:
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                num_before = i - num
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                if num_before >= 0:
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                    dp[i] += dp[num_before]
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        return dp[target]