| comments | difficulty | edit_url |
|---|---|---|
true |
中等 |
给定一棵二叉树，设计一个算法，创建含有某一深度上所有节点的链表（比如，若一棵树的深度为 D，则会创建出 D 个链表）。返回一个包含所有深度的链表的数组。
示例：
输入：[1,2,3,4,5,null,7,8]
1
/ \
2 3
/ \ \
4 5 7
/
8
输出：[[1],[2,3],[4,5,7],[8]]
我们可以使用 BFS 层序遍历的方法，每次遍历一层，将当前层的节点值存入链表中，然后将链表加入到结果数组中。
时间复杂度
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def listOfDepth(self, tree: TreeNode) -> List[ListNode]:
ans = []
q = deque([tree])
while q:
dummy = cur = ListNode(0)
for _ in range(len(q)):
node = q.popleft()
cur.next = ListNode(node.val)
cur = cur.next
if node.left:
q.append(node.left)
if node.right:
q.append(node.right)
ans.append(dummy.next)
return ans/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode[] listOfDepth(TreeNode tree) {
List<ListNode> ans = new ArrayList<>();
Deque<TreeNode> q = new ArrayDeque<>();
q.offer(tree);
while (!q.isEmpty()) {
ListNode dummy = new ListNode(0);
ListNode cur = dummy;
for (int k = q.size(); k > 0; --k) {
TreeNode node = q.poll();
cur.next = new ListNode(node.val);
cur = cur.next;
if (node.left != null) {
q.offer(node.left);
}
if (node.right != null) {
q.offer(node.right);
}
}
ans.add(dummy.next);
}
return ans.toArray(new ListNode[0]);
}
}/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
vector<ListNode*> listOfDepth(TreeNode* tree) {
vector<ListNode*> ans;
queue<TreeNode*> q{{tree}};
while (!q.empty()) {
ListNode* dummy = new ListNode(0);
ListNode* cur = dummy;
for (int k = q.size(); k; --k) {
TreeNode* node = q.front();
q.pop();
cur->next = new ListNode(node->val);
cur = cur->next;
if (node->left) {
q.push(node->left);
}
if (node->right) {
q.push(node->right);
}
}
ans.push_back(dummy->next);
}
return ans;
}
};/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
/**
* Definition for singly-linked list.
* type ListNode struct {
* Val int
* Next *ListNode
* }
*/
func listOfDepth(tree *TreeNode) (ans []*ListNode) {
q := []*TreeNode{tree}
for len(q) > 0 {
dummy := &ListNode{}
cur := dummy
for k := len(q); k > 0; k-- {
node := q[0]
q = q[1:]
cur.Next = &ListNode{Val: node.Val}
cur = cur.Next
if node.Left != nil {
q = append(q, node.Left)
}
if node.Right != nil {
q = append(q, node.Right)
}
}
ans = append(ans, dummy.Next)
}
return
}/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
/**
* Definition for singly-linked list.
* class ListNode {
* val: number
* next: ListNode | null
* constructor(val?: number, next?: ListNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
* }
*/
function listOfDepth(tree: TreeNode | null): Array<ListNode | null> {
const ans: Array<ListNode | null> = [];
const q: Array<TreeNode | null> = [tree];
while (q.length) {
const dummy = new ListNode();
let cur = dummy;
for (let k = q.length; k; --k) {
const { val, left, right } = q.shift()!;
cur.next = new ListNode(val);
cur = cur.next;
left && q.push(left);
right && q.push(right);
}
ans.push(dummy.next);
}
return ans;
}// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
// pub val: i32,
// pub left: Option<Rc<RefCell<TreeNode>>>,
// pub right: Option<Rc<RefCell<TreeNode>>>,
// }
//
// impl TreeNode {
// #[inline]
// pub fn new(val: i32) -> Self {
// TreeNode {
// val,
// left: None,
// right: None
// }
// }
// }
// Definition for singly-linked list.
// #[derive(PartialEq, Eq, Clone, Debug)]
// pub struct ListNode {
// pub val: i32,
// pub next: Option<Box<ListNode>>
// }
//
// impl ListNode {
// #[inline]
// fn new(val: i32) -> Self {
// ListNode {
// next: None,
// val
// }
// }
// }
use std::cell::RefCell;
use std::collections::VecDeque;
use std::rc::Rc;
impl Solution {
pub fn list_of_depth(tree: Option<Rc<RefCell<TreeNode>>>) -> Vec<Option<Box<ListNode>>> {
let mut res = vec![];
if tree.is_none() {
return res;
}
let mut q = VecDeque::new();
q.push_back(tree);
while !q.is_empty() {
let n = q.len();
let mut demmy = Some(Box::new(ListNode::new(0)));
let mut cur = &mut demmy;
for _ in 0..n {
if let Some(node) = q.pop_front().unwrap() {
let mut node = node.borrow_mut();
if node.left.is_some() {
q.push_back(node.left.take());
}
if node.right.is_some() {
q.push_back(node.right.take());
}
cur.as_mut().unwrap().next = Some(Box::new(ListNode::new(node.val)));
cur = &mut cur.as_mut().unwrap().next;
}
}
res.push(demmy.as_mut().unwrap().next.take());
}
res
}
}/* class TreeNode {
* var val: Int
* var left: TreeNode?
* var right: TreeNode?
*
* init(_ val: Int) {
* self.val = val
* self.left = nil
* self.right = nil
* }
* }
*/
/* class ListNode {
* var val: Int
* var next: ListNode?
*
* init(_ val: Int) {
* self.val = val
* self.next = nil
* }
* }
*/
class Solution {
func listOfDepth(_ tree: TreeNode?) -> [ListNode?] {
var ans = [ListNode?]()
guard let tree = tree else { return ans }
var q = [TreeNode]()
q.append(tree)
while !q.isEmpty {
let dummy = ListNode(0)
var cur = dummy
for _ in 0..<q.count {
let node = q.removeFirst()
cur.next = ListNode(node.val)
cur = cur.next!
if let left = node.left {
q.append(left)
}
if let right = node.right {
q.append(right)
}
}
ans.append(dummy.next)
}
return ans
}
}