输入描述:

{ node: 'root', next: [ { node: 'second_root' }, { node: 'second_child', next: [{ node: 'second_child_1', next: { node: 'second_child_1_1' } }, { node: 'second_child_2' }] }, { node: 'third_root', next: { node: 'third_child' , next: [{ node: 'third_child_1', next: { node: 'third_child_1_1' } }, { node: 'third_child_2' }] } } ] }

输出描述:

数组输出规范1）数组应被左右中括号括起；2）数组的元素间由','相隔；3）各节点在数组中的顺序应和其在输入中出现的次序一致；4）节点名保证为不超过30个字符的字符串，仅含大小写字母、数字及下划线，输出时应用双引号括起；5）输出的字符串不应有多余的空格。

{ node: 'root', next: [ { node: 'second_root' }, { node: 'second_child', next: [{ node: 'second_child_1', next: { node: 'second_child_1_1' } }, { node: 'second_child_2' }] }, { node: 'third_root', next: { node: 'third_child' , next: [{ node: 'third_child_1', next: { node: 'third_child_1_1' } }, { node: 'third_child_2' }] } } ] }

["root","second_child","third_child"]