# How Do You Make a Tree in Data Structure?

//

Heather Bennett

Creating a tree in data structure is a fundamental concept that every programmer needs to understand. A tree is a hierarchical data structure that consists of nodes connected by edges. In this article, we will explore how to create a tree and perform various operations on it.

## Understanding Trees

In computer science, a tree is an abstract data type that represents a hierarchical structure. It resembles an upside-down tree, where the topmost node is called the root, and every other node is connected to the root or another node through edges.

Each node in a tree can have zero or more child nodes, except for the leaf nodes which have no child nodes. The depth of a node represents the number of edges from the root to that particular node.

## Creating a Tree

To create a tree in data structure, we need to define the structure of each node and establish connections between them. Let’s start by defining our Node class:

```<code>
class Node {
constructor(data) {
this.data = data;
this.children = [];
}
}
</code>
```

In this code snippet, we define our Node class with two properties: ‘data’ to store the value of each node and ‘children’ as an empty array to hold its child nodes. Now, let’s create our Tree class:

```<code>
class Tree {
constructor() {
this.root = null;
}
}
</code>
```

In the Tree class, we initialize ‘root’ as null because initially our tree is empty. Now, let’s add methods to our Tree class for insertion and traversal:

### Insertion

To insert a new node in the tree, we need to specify its parent node and add it as a child of that parent. Let’s define the ‘insert’ method:

```<code>
class Tree {
// previous code..

insert(data, parentData) {
const node = new Node(data);

if (this.root === null) {
this.root = node;
return;
}

this.insertNode(this.root, data, parentData);
}

insertNode(node, data, parentData) {
if (node.data === parentData) {
node.children.push(new Node(data));
return;
}

for (const child of node.children) {
this.insertNode(child, data, parentData);
}
}
}
</code>
```

In our ‘insert’ method, we first create a new Node object with the given data. If the tree is empty, we set the newly created node as the root. Otherwise, we call the recursive ‘insertNode’ method to find the parent node and add the new node as its child.

### Traversal

Tree traversal allows us to visit every node in the tree. There are commonly used traversal techniques such as depth-first traversal (pre-order, in-order, post-order) and breadth-first traversal (level order). Let’s implement depth-first pre-order traversal:

preOrderTraversal() {
this.preOrder(this.root);
}

preOrder(node) {
if (node === null) return;

console.log(node.data);

for (const child of node.preOrder(child);
}
}
}
</code>

In our ‘preOrderTraversal’ method, we call the recursive ‘preOrder’ method starting from the root. This method prints the data of each node and recursively traverses through its children.

## Conclusion

In conclusion, creating a tree in data structure involves defining a Node class, establishing connections between nodes, and implementing various operations like insertion and traversal. Understanding trees is crucial for solving many real-world problems efficiently. By incorporating trees into your programming knowledge, you will be equipped with a powerful tool to organize and manipulate hierarchical data.