将列表转换为字典并添加重复的键值

def list_to_dict(lst):
    result_dict = {}
    for item in lst:
        if item in result_dict:
            if isinstance(result_dict[item], list):
                result_dict[item].append(item)
            else:
                result_dict[item] = [result_dict[item], item]
        else:
            result_dict[item] = item
    return result_dict

# 示例用法
my_list = ['a', 'b', 'a', 'c', 'b']
my_dict = list_to_dict(my_list)
print(my_dict)

{'a': ['a', 'a'], 'b': ['b', 'b'], 'c': 'c'}