LeetCode 剑指 Offer II 028. 展平多级双向链表
文章目录
题目描述
LeetCode 剑指 Offer II 028. 展平多级双向链表
提示:
节点数目不超过 1000
1 <= Node.val <= 10^5
一、解题关键词
二、解题报告
1.思路分析
2.时间复杂度
3.代码示例
/*
// 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) {
dfs(head);
return head;
}
Node dfs(Node head){
Node cur = head;
Node last = null;
while( cur != null){
Node next = cur.next;
if(cur.child != null){
Node childLast = dfs(cur.child);
next = cur.next;
//将node 与child 相连
cur.next = cur.child;
cur.child.prev = cur;
//如果next
if(next != null){
childLast.next = next;
next.prev = childLast;
}
cur.child = null;
last = childLast;
} else{
last = cur;
}
cur = next;
}
return last;
}
}
2.知识点
总结
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