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1490. Clone N-ary Tree

Description

Given a root of an N-ary tree, return a deep copy (clone) of the tree.

Each node in the n-ary tree contains a val (int) and a list (List[Node]) of its children.

class Node {
    public int val;
    public List<Node> children;
}

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:

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

Example 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,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]

 

Constraints:

• The depth of the n-ary tree is less than or equal to 1000.
• The total number of nodes is between [0, 104].

 

Follow up: Can your solution work for the graph problem?

Solutions

DFS.

• Java
• C++
• Python
• Go

• /*
  // Definition for a Node.
  class Node {
      public int val;
      public List<Node> children;
  
  
      public Node() {
          children = new ArrayList<Node>();
      }
  
      public Node(int _val) {
          val = _val;
          children = new ArrayList<Node>();
      }
  
      public Node(int _val,ArrayList<Node> _children) {
          val = _val;
          children = _children;
      }
  };
  */
  
  class Solution {
      public Node cloneTree(Node root) {
          if (root == null) {
              return null;
          }
          ArrayList<Node> children = new ArrayList<>();
          for (Node child : root.children) {
              children.add(cloneTree(child));
          }
          return new Node(root.val, children);
      }
  }
  

• /*
  // Definition for a Node.
  class Node {
  public:
      int val;
      vector<Node*> children;
  
      Node() {}
  
      Node(int _val) {
          val = _val;
      }
  
      Node(int _val, vector<Node*> _children) {
          val = _val;
          children = _children;
      }
  };
  */
  
  class Solution {
  public:
      Node* cloneTree(Node* root) {
          if (!root) {
              return root;
          }
          vector<Node*> children;
          for (Node* child : root->children) {
              children.emplace_back(cloneTree(child));
          }
          return new Node(root->val, children);
      }
  };
  

• """
  # Definition for a Node.
  class Node:
      def __init__(self, val=None, children=None):
          self.val = val
          self.children = children if children is not None else []
  """
  
  
  class Solution:
      def cloneTree(self, root: 'Node') -> 'Node':
          if root is None:
              return None
          children = [self.cloneTree(child) for child in root.children]
          return Node(root.val, children)
  
  

• /**
   * Definition for a Node.
   * type Node struct {
   *     Val int
   *     Children []*Node
   * }
   */
  
  func cloneTree(root *Node) *Node {
  	if root == nil {
  		return nil
  	}
  	children := []*Node{}
  	for _, child := range root.Children {
  		children = append(children, cloneTree(child))
  	}
  	return &Node{root.Val, children}
  }
  

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