Arithmetic Slices LeetCode solution in Python

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class Solution:
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    def numberOfArithmeticSlices(self, nums: List[int]) -> int:
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        ans = 0
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        table = [0] * len(nums)
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        for r in range(2, len(nums)):
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            diff1 = nums[r] - nums[r - 1]
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            diff2 = nums[r - 1] - nums[r - 2]
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            if diff1 == diff2:
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                table[r] = table[r - 1] + 1
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                ans += table[r - 1] + 1
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        return ans