# Replace every node with depth in N-ary Generic Tree

Given an array arr[] representing a Generic(N-ary) tree. The task is to replace the node data with the depth(level) of the node. Assume level of root to be 0.

Array Representation: The N-ary tree is serialized in the array arr[] using level order traversal as described below:

• The input is given as a level order traversal of N-ary Tree.
• The first element of the array arr[] is the root node.
• Then, followed by a number N, which denotes the number of children of the previous node. Value zero denotes Null Node.

Examples:

Input: arr[] = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 }
Below is the N-ary Tree of the above array level order traversal: Output:
Below is the representation of the above output: Input: arr[] = {1, 3, 2, 3, 4, 2, 5, 6, 0, 0, 2, 8, 9}
Below is the N-ary Tree of the above array level order traversal: Output:
Below is the representation of the above output: ## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

• Traverse the tree starting from root.
• While traversing pass depth of node as a parameter.
• Track depth by passing it as 0 for root and (1 + currrent level) for children.

Below is the implementation of the above approach:

 `// C++ program to implement node with ` `// it's depth value ` `#include ` `using` `namespace` `std; ` ` `  `// Treenode class using template ` `template` `<``typename` `T> ` `class` `TreeNode { ` `public``: ` `    ``// To store node value ` `    ``T data; ` ` `  `    ``// Pointer to TreeNode to store ` `    ``// the child node ` `    ``vector*> children; ` ` `  `    ``// Constructor to assign data ` `    ``// to node ` `    ``TreeNode(T data) ` `    ``{ ` `        ``this``->data = data; ` `    ``} ` ` `  `    ``// Destructors to delete a node ` `    ``~TreeNode() ` `    ``{ ` `        ``for` `(``int` `i = 0; ` `             ``i < children.size(); i++) { ` `            ``delete` `children[i]; ` `        ``} ` `    ``} ` `}; ` ` `  `// Function to take input level wise ` `// i.e., in level order traversal ` `TreeNode<``int``>* takeInputLevelWise(``int` `arr[]) ` `{ ` `    ``int` `idx = 1; ` ` `  `    ``// Input root ` `    ``int` `rootData = arr; ` ` `  `    ``// Initialize tree with a root node ` `    ``TreeNode<``int``>* root ` `        ``= ``new` `TreeNode<``int``>(rootData); ` ` `  `    ``// Intialise queue for appending ` `    ``// node as a child of parent in ` `    ``// N-ary tree ` `    ``queue*> pendingNodes; ` ` `  `    ``// Push the root node in queue ` `    ``pendingNodes.push(root); ` ` `  `    ``// While queue is not empty append ` `    ``// child to the root ` `    ``while` `(pendingNodes.size() != 0) { ` ` `  `        ``// Take the first node ` `        ``TreeNode<``int``>* front ` `            ``= pendingNodes.front(); ` `        ``pendingNodes.pop(); ` ` `  `        ``// Input number of child ` `        ``int` `numChild = arr[idx]; ` `        ``idx++; ` ` `  `        ``for` `(``int` `i = 0; i < numChild; i++) { ` ` `  `            ``int` `childData = arr[idx]; ` `            ``idx++; ` ` `  `            ``// Make child Node ` `            ``TreeNode<``int``>* child ` `                ``= ``new` `TreeNode<``int``>(childData); ` ` `  `            ``// Append child node to ` `            ``// it's parent ` `            ``front->children.push_back(child); ` `            ``pendingNodes.push(child); ` `        ``} ` `    ``} ` `    ``return` `root; ` `} ` ` `  `// Function to print each node data ` `// in level order ` `void` `printLevelATNewLine(TreeNode<``int``>* root) ` `{ ` `    ``queue*> q; ` `    ``q.push(root); ` `    ``q.push(NULL); ` `    ``while` `(!q.empty()) { ` ` `  `        ``TreeNode<``int``>* first = q.front(); ` `        ``q.pop(); ` ` `  `        ``if` `(first == NULL) { ` `            ``if` `(q.empty()) { ` `                ``break``; ` `            ``} ` `            ``cout << endl; ` `            ``q.push(NULL); ` `            ``continue``; ` `        ``} ` ` `  `        ``cout << first->data << ``" "``; ` ` `  `        ``for` `(``int` `i = 0; ` `             ``i < first->children.size(); i++) { ` `            ``q.push(first->children[i]); ` `        ``} ` `    ``} ` `} ` ` `  `// Helper function to replace the ` `// node data with their level value ` `void` `helper(TreeNode<``int``>* root, ` `            ``int` `depth) ` `{ ` ` `  `    ``// Replace the node data with ` `    ``// it's depth ` `    ``root->data = depth; ` `    ``for` `(``int` `i = 0; ` `         ``i < root->children.size(); i++) { ` ` `  `        ``helper(root->children[i], depth + 1); ` `    ``} ` `} ` ` `  `// Function to replace with depth ` `void` `replaceWithDepthValue(TreeNode<``int``>* root) ` `{ ` `    ``helper(root, 0); ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` ` `  `    ``// Given level order traversal in ` `    ``// the array arr[] ` `    ``int` `arr[] = { 10, 3, 20, 30, 40, 2, ` `                  ``40, 50, 0, 0, 0, 0 }; ` ` `  `    ``// Intialise Tree ` `    ``TreeNode<``int``>* root; ` `    ``root = takeInputLevelWise(arr); ` ` `  `    ``// Function call to replace with ` `    ``// depth value ` `    ``replaceWithDepthValue(root); ` ` `  `    ``// Function call to print ` `    ``// in level order ` `    ``printLevelATNewLine(root); ` `    ``return` `0; ` `} `

Output:

```0
1 1 1
2 2
```

Time Complexity: O(N), where N is the number of nodes in Tree.
Auxiliary Space: O(N), where N is the number of nodes in Tree.

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