construct a linked list from 2d matrix in c#

Csharp program for construct a linked list from 2d matrix. Here problem description and other solutions.

// Include namespace system
using System;
// Csharp program for
// Construct a linked list from 2D matrix
public class LinkNode
{
	public int data;
	public LinkNode next;
	public LinkNode down;
	public LinkNode(int data)
	{
		this.data = data;
		this.next = null;
		this.down = null;
	}
}
public class DoublyLinkedList
{
	public LinkNode head;
	public DoublyLinkedList()
	{
		// Set inital value
		this.head = null;
	}
	public void display()
	{
		if (this.head == null)
		{
			Console.Write("Empty linked list");
		}
		else
		{
			var front = this.head;
			LinkNode right = null;
			while (front != null)
			{
				right = front;
				while (right != null)
				{
					Console.Write(right.data + "  ");
					right = right.next;
				}
				Console.Write("\n");
				// Visit to down node
				front = front.down;
			}
		}
	}
	public void insertData(int[, ] matrix, int rows, int cols)
	{
		// Some auxiliary variables
		LinkNode levelHead = null;
		LinkNode root = null;
		LinkNode perv = null;
		var i = 0;
		var j = 0;
		// Add first row elements into result list 
		while (i < cols)
		{
			if (this.head == null)
			{
				// Add first node
				this.head = new LinkNode(matrix[0, i]);
				levelHead = this.head;
			}
			else
			{
				// next head
				levelHead.next = new LinkNode(matrix[0, i]);
				levelHead = levelHead.next;
			}
			i++;
		}
		// Get first element    
		levelHead = this.head;
		i = 1;
		// Add all the bottom element of each column
		while (i < rows)
		{
			root = null;
			perv = root;
			while (j < cols)
			{
				levelHead.down = new LinkNode(matrix[i, j]);
				if (root == null)
				{
					root = levelHead.down;
					perv = root;
				}
				else
				{
					perv.next = levelHead.down;
					perv = levelHead.down;
				}
				levelHead = levelHead.next;
				j++;
			}
			levelHead = root;
			// reset col
			j = 0;
			// change row
			i++;
		}
	}
	public static void Main(String[] args)
	{
		var dll = new DoublyLinkedList();
		// Create 2D metrix
		int[, ] matrix = {
			{
				1 , 6 , 9 , 2 , -9
			},
			{
				2 , 5 , -5 , 7 , 1
			},
			{
				3 , 4 , 1 , 8 , 2
			}
		};
		var rows = matrix.GetLength(0);
		var cols = matrix.GetLength(1);
		dll.insertData(matrix, rows, cols);
		dll.display();
	}
}

Output

1  6  9  2  -9
2  5  -5  7  1
3  4  1  8  2