Given an n-ary tree, return the preorder traversal of its nodes' values.

For example, given a 3-ary tree:

Return its preorder traversal as: [1,3,5,6,2,4].

Note: Recursive solution is trivial, could you do it iteratively?

Recursion Method:

"""
# Definition for a Node.
class Node(object):
def __init__(self, val, children):
self.val = val
self.children = children
"""
class Solution(object):
def preorder(self, root):
"""
:type root: Node
:rtype: List[int]
"""
l=[] def subpreorderfun(r):
if r:
l.append(r.val)
for c in r.children:
subpreorderfun(c) subpreorderfun(root) return l

  

Iteration Method:

"""
# Definition for a Node.
class Node(object):
def __init__(self, val, children):
self.val = val
self.children = children
"""
class Solution(object):
def preorder(self, root):
"""
:type root: Node
:rtype: List[int]
"""
l=[]
q=[root] if root:
p=[]
while q:
a=q.pop(0)
l.append(a.val) for c in a.children:
p.append(c) n=len(p)
for i in range(n):
q=[p.pop()]+q return l

  

[LeetCode&Python] Problem 589. N-ary Tree Preorder Traversal的更多相关文章

  1. 【Leetcode】【Medium】Binary Tree Preorder Traversal

    Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tr ...

  2. 【leetcode刷题笔记】Binary Tree Preorder Traversal

    Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tr ...

  3. [LeetCode&Python] Problem 427. Construct Quad Tree

    We want to use quad trees to store an N x N boolean grid. Each cell in the grid can only be true or ...

  4. [LeetCode&Python] Problem 226. Invert Binary Tree

    Invert a binary tree. Example: Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9 6 3 1 Tr ...

  5. [Leetcode 144]二叉树前序遍历Binary Tree Preorder Traversal

    [题目] Given a binary tree, return the preordertraversal of its nodes' values. Example: Input: [1,null ...

  6. LeetCode 589. N叉树的前序遍历(N-ary Tree Preorder Traversal)

    589. N叉树的前序遍历 589. N-ary Tree Preorder Traversal LeetCode589. N-ary Tree Preorder Traversal 题目描述 给定一 ...

  7. LeetCode 144. 二叉树的前序遍历(Binary Tree Preorder Traversal)

    144. 二叉树的前序遍历 144. Binary Tree Preorder Traversal 题目描述 给定一个二叉树,返回它的 前序 遍历. LeetCode144. Binary Tree ...

  8. 【leetcode_easy】589. N-ary Tree Preorder Traversal

    problem 589. N-ary Tree Preorder Traversal N叉树的前序遍历 首先复习一下树的4种遍历,前序.中序.后序和层序.其中,前序.中序和后序是根据根节点的顺序进行区 ...

  9. [LeetCode] N-ary Tree Preorder Traversal N叉树的前序遍历

    Given an n-ary tree, return the preorder traversal of its nodes' values. For example, given a 3-ary  ...

随机推荐

  1. Qt for Embedded Linux

    1. Qt for Embedded Linux http://doc.qt.io/qt-5/embedded-linux.html 2. Installing Qt for Embedded Lin ...

  2. shuoj 418 丢史蒂芬妮(素数筛+sg函数)

    丢史蒂芬妮 代码: #include<bits/stdc++.h> using namespace std; +; int SG[N][N]; bool S[N]; vector<i ...

  3. HDU 6130 Kolakoski

    Kolakoski 思路: 从前往后扩展,前后构成映射关系. 代码: #include<bits/stdc++.h> using namespace std; #define ll lon ...

  4. Java基础九--抽象类

    Java基础九--抽象类 一.抽象类介绍 /*抽象类:抽象:笼统,模糊,看不懂!不具体. 特点:1,方法只有声明没有实现时,该方法就是抽象方法,需要被abstract修饰. 抽象方法必须定义在抽象类中 ...

  5. memcached-1.4.20 主要启动流程笔记

    以下笔记主要是关注tcp模式下memcached的启动过程. main() 设置信号处理函数为sig_handler() 初始化系统设置,保存在全局变量settings里面 settings_init ...

  6. Perfect Groups CodeForces - 980D

    链接 题目大意: 定义一个问题: 求集合$S$的最小划分数,使得每个划分内任意两个元素积均为完全平方数. 给定$n$元素序列$a$, 对$a$的所有子区间, 求出上述问题的结果, 最后要求输出所有结果 ...

  7. python-day33--进程间通信(IPC)

    方式:队列(推荐使用) 一.基本情况 1.可以往队列里放任意类型的数据 2. 队列:先进先出 3. q=Queue(3) #可以设置队列中最多可以进入多少个值,也可以不设置 q.put('first' ...

  8. c++中的引用详解

    什么是引用? 引用是C++语言的一个特殊的数据类型描述,用于在程序的不同的部分使用两个以上的变量名指向同一块地址,使得对其中任何一个变量的操作实际上都是对同一地址单元进行的. 使用时的注意事项: 引用 ...

  9. cf188C(最大子段和&&思维)

    C. Functions again time limit per test 1 second memory limit per test 256 megabytes input standard i ...

  10. HDU-5001 Walk (概率DP)

    Problem Description I used to think I could be anything, but now I know that I couldn't do anything. ...