You are given a doubly linked list which in addition to the next and previous pointers, it could have a child pointer, which may or may not point to a separate doubly linked list. These child lists may have one or more children of their own, and so on, to produce a multilevel data structure, as shown in the example below.
Flatten the list so that all the nodes appear in a single-level, doubly linked list. You are given the head of the first level of the list.
/* // Definition for a Node. class Node { public int val; public Node prev; public Node next; public Node child; }; */ class Solution { public Node flatten(Node head) { if (head == null) { return head; } Node cur = head; while (cur != null) { if (cur.child != null) { Node right = cur.next; cur.next = flatten(cur.child); cur.next.prev = cur; cur.child = null; while (cur.next != null) { cur = cur.next; } if (right != null) { cur.next = right; cur.next.prev = cur; } } cur = cur.next; } return head; } }
[LC] 430. Flatten a Multilevel Doubly Linked List
原文：https://www.cnblogs.com/xuanlu/p/12306590.html