### findOriginalArray 
from typing import *
def f_gold(changed: List[int]) -> List[int]:
    if len(changed) % 2 != 0:
        return []
    n = 100010
    counter = [0] * n
    for x in changed:
        counter[x] += 1
    if counter[0] % 2 != 0:
        return []
    res = [0] * (counter[0] // 2)
    for i in range(1, n):
        if counter[i] == 0:
            continue
        if i * 2 > n or counter[i] > counter[i * 2]:
            return []
        res.extend([i] * counter[i])
        counter[i * 2] -= counter[i]
    return res