Check If Array Pairs Are Divisible by k LeetCode solution in Python

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# Runtime: 556 ms (Top 81.4%) | Memory: 30.00 MB (Top 97.8%)
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class Solution:
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    def canArrange(self, arr: List[int], k: int) -> bool:
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        # The idea is to count the residues
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        # If every residue has the counter residue
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        # such that x+y == k,then we found a pair
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        count = [0] * k
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        for num in arr:
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            count[num % k] += 1
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        # Now since we have 0,1,2,.....k-1 as residues
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        # If count[1] == count[k-1],pairs+=count[1]
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        # since we have odd number of complimenting residues,
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        # we should also care about residue=0 and residue=k//2
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        i, j = 1, k - 1
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        pairs = 0
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        while i < j:
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            if count[i] != count[j]:
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                return False
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            pairs += count[i]
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            i += 1
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            j -= 1
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        if pairs > 0 and i == j:
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            pairs += count[i] / 2
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        pairs += count[0] / 2
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        n = len(arr)
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        return pairs == n // 2