将嵌套字典中某个类型的所有匹配项提升到顶级键

def flatten_dict(d, target_type):
    result = {}
    for key, value in d.items():
        if isinstance(value, target_type):
            result[key] = value
        elif isinstance(value, dict):
            nested_result = flatten_dict(value, target_type)
            for nested_key, nested_value in nested_result.items():
                result[nested_key] = nested_value
    return result

# 示例用法
nested_dict = {
    'key1': {
        'subkey1': 'value1',
        'subkey2': 'value2'
    },
    'key2': {
        'subkey3': 'value3',
        'subkey4': 'value4'
    },
    'key3': {
        'subkey5': 'value5',
        'subkey6': 'value6'
    }
}

target_type = str
result = flatten_dict(nested_dict, target_type)
print(result)