BinarySearch 0644 Partition List to Pairs that Are Divisible by K

Problem statement

https://binarysearch.com/problems/Partition-List-to-Pairs-that-Are-Divisible-by-K/

Solution

For each reminder calculate number of values we have, then check cases 0 and k//2.

Complexity

It is O(n) for time and space.

Code

class Solution:
    def solve(self, nums, k):
        cnt = Counter()
        for num in nums:
            cnt[num%k] += 1
        for i in cnt:
            if i == 0 or i*2 == k:
                if cnt[i] % 2 == 1: return False
            else:
                if cnt[i] != cnt[k - i]: return False
        return True