在Python中标识列表中的重复值

def find_duplicates(lst):
    duplicates = set()
    seen = set()
    for item in lst:
        if item in seen:
            duplicates.add(item)
        else:
            seen.add(item)
    return list(duplicates)

# 示例
lst = [1, 2, 3, 2, 1, 5, 6, 5]
print(find_duplicates(lst))  # 输出: [1, 2, 5]

def find_duplicates(lst):
    count = {}
    for item in lst:
        if item in count:
            count[item] += 1
        else:
            count[item] = 1
    duplicates = [item for item, freq in count.items() if freq > 1]
    return duplicates

# 示例
lst = [1, 2, 3, 2, 1, 5, 6, 5]
print(find_duplicates(lst))  # 输出: [1, 2, 5]

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

# 示例
lst = [1, 2, 3, 2, 1, 5, 6, 5]
print(find_duplicates(lst))  # 输出: [1, 2, 5]

def find_duplicates(lst):
    seen = set()
    duplicates = set()
    for item in lst:
        if item in seen:
            duplicates.add(item)
        else:
            seen.add(item)
    return list(duplicates)