这样的数组如何让它树状显示呢

Array

(

    [1] => Array

        (

            [id] => 1

            [name] => 世界

            [pid] => 0

            [2] => Array

                (

                    [id] => 2

                    [name] => 中国

                    [pid] => 1

                    [4] => Array

                        (

                            [id] => 4

                            [name] => 湖南

                            [pid] => 2

                        )



                )



            [3] => Array

                (

                    [id] => 3

                    [name] => 美国

                    [pid] => 1

                )