在Python中搜索列表中的重复项

def find_duplicates(lst):
    duplicates = set([x for x in lst if lst.count(x) > 1])
    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):
    seen = {}
    duplicates = []
    for x in lst:
        if x not in seen:
            seen[x] = 1
        else:
            if seen[x] == 1:
                duplicates.append(x)
            seen[x] += 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):
    seen = set()
    duplicates = set()
    for x in lst:
        if x in seen:
            duplicates.add(x)
        else:
            seen.add(x)
    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):
    seen = set()
    for x in lst:
        if x in seen:
            yield x
        else:
            seen.add(x)

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