N-Ary Tree Preorder Traversal Problem


Description

LeetCode Problem 589.

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

Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)

Example 1:

1
2
Input: root = [1,null,3,2,4,null,5,6]
Output: [1,3,5,6,2,4]

Example 2:

1
2
Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [1,2,3,6,7,11,14,4,8,12,5,9,13,10]

Constraints:

  • The number of nodes in the tree is in the range [0, 10^4].
  • 0 <= Node.val <= 10^4
  • The height of the n-ary tree is less than or equal to 1000.


Sample C++ Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
class Solution {
private:
    void travel(Node* root, vector<int>& result) {
        if (root == nullptr) {
            return;
        }
        
        result.push_back(root -> val);
        for (Node* child : root -> children) {
            travel(child, result);
        }
    }
public:
    vector<int> preorder(Node* root) {
        vector<int> result;
        travel(root, result);
        return result;
    }
};




Related Posts

Max Area Of Island Problem

LeetCode 695. You are given an m x n binary...

Employee Importance Problem

LeetCode 690. You have a data structure of employee information,...

Cracking The Safe Problem

LeetCode 753. There is a safe protected by a password....

Couples Holding Hands Problem

LeetCode 765. There are n couples sitting in 2n seats...

Contain Virus Problem

LeetCode 749. A virus is spreading rapidly, and your task...

Construct String From Binary Tree Problem

LeetCode 606. Given the root of a binary tree, construct...