1346. Check If N and Its Double Exist.py

class Solution:
    def checkIfExist(self, arr: List[int]) -> bool:

        seen = set()

        for num in arr:
            if num * 2 in seen or (num % 2 == 0 and num // 2 in seen):
                return True
            
            seen.add(num)
            
        return False