在python中查找列表中的重复元素需要帮助

def find_duplicates(lst):
    duplicates = []
    for item in lst:
        if lst.count(item) > 1 and item not in duplicates:
            duplicates.append(item)
    return duplicates

def find_duplicates(lst):
    return list(set([x for x in lst if lst.count(x) > 1]))

from collections import Counter

def find_duplicates(lst):
    counter = Counter(lst)
    return [item for item, count in counter.items() if count > 1]