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C# program to implement Pre-order traversal in Binary Tree

Here, we are going to learn how to implement Pre-order traversal in Binary Tree in C#? By Nidhi Last updated : March 28, 2023

Here, we will implement a binary tree then traverse a binary tree into pre-order.

Preorder traversal in Binary Tree Implementation in C#

The source code to implement Pre-order traversal in Binary Tree is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

// C# program to implement Pre-order traversal 
// in Binary Tree

using System;
using System.Collections.Generic;
using System.Text;

class Node {
  public int item;
  public Node left_ptr;
  public Node right_ptr;

}
class BinaryTree {
  public Node root;
  public Node GetRoot() {
    return root;
  }
  public void Preorder_Traverse(Node rootNode) {
    if (rootNode != null) {
      Console.Write("{0} ", rootNode.item);
      Preorder_Traverse(rootNode.left_ptr);
      Preorder_Traverse(rootNode.right_ptr);
    }
  }
  public void InsertItem(int item) {
    Node curNode;
    Node parentNode;
    Node node = new Node();

    node.item = item;

    if (root != null) {
      curNode = root;

      while (true) {
        parentNode = curNode;
        if (item < curNode.item) {
          curNode = curNode.left_ptr;
          if (curNode == null) {
            parentNode.left_ptr = node;
            break;
          }
        } else {
          curNode = curNode.right_ptr;
          if (curNode == null) {
            parentNode.right_ptr = node;
            break;
          }
        }
      }
    } else {
      root = node;
    }
  }
}

class Demo {
  static void Main(string[] args) {
    BinaryTree tree = new BinaryTree();

    tree.InsertItem(10);
    tree.InsertItem(15);
    tree.InsertItem(35);
    tree.InsertItem(26);
    tree.InsertItem(47);
    tree.InsertItem(34);
    tree.InsertItem(90);

    Console.WriteLine("Preorder Traversal : ");
    tree.Preorder_Traverse(tree.GetRoot());
    Console.WriteLine(" ");
  }
}

Output

Preorder Traversal :
10 15 35 26 34 47 90
Press any key to continue . . .

Explanation

In the above program, we created three classes Node, BinaryTree, and Demo. The code class contains the item and left and a right pointer to the node.

The BinaryTree class is used to implement binary tree, it contains GetRoot(), InsertItem(), and Preorder_Traverse() methods.

The GetRoot() method returns the root node, and InsertItem() method is used to insert the item into the tree. The Preorder_Traverse() method is used to traverse the tree into pre-order.

Now look to the Demo class, the Demo class contains the Main() method, here we created an object of BinaryTree class and then insert the items into the tree and then traverse them into pre-order traversal.

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