Number of Boomerangs LeetCode solution in Python

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class Solution:
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    def numberOfBoomerangs(self, points: List[List[int]]) -> int:
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        def sq(a):
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            return a * a
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        def euclid(a, b, c, d):
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            dist = sq(a - c) + sq(b - d)
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            return sq(dist)
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        n = len(points)
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        res = 0
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        for i in range(n):
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            count = defaultdict(lambda: 0)
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            for j in range(n):
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                d = euclid(points[i][0], points[i][1], points[j][0], points[j][1])
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                res += count[d] * 2
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                count[d] += 1
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        return res