# 1346. Check If N and Its Double Exist """ given an array 'arr' of integers, check if there exists two indices 'i' and 'j' such that 'i != j', '0 <= i, j < arr.length', and 'arr[i] == 2 * arr[j]' """ class Solution(object): def checkIfExist(self, arr): """ :type arr: List[int] :rtype: bool """ seen = set() for i in arr: if 2 * i in seen or i / 2 in seen: return True seen.add(i) return False if __name__ == "__main__": obj = Solution() print(obj.checkIfExist(arr=[10, 2, 5, 3])) print(obj.checkIfExist(arr=[3, 1, 7, 11]))