ColumnOrder Implementation

Program.cs

/* Given the following binary tree
      6
     / \
    3   4
   /   / \
  5   1   0
   \     /
    2   8
   / \
  9   7
  
*/

using System;
using System.Collections.Generic;

namespace ColumnOrder{
class ColumnOrder {
 public static void Main(string[] args){
   Node a = new Node(6);
   Node b = new Node(3);
   Node c = new Node(5);
   Node d = new Node(2);
   Node e = new Node(9);
   Node f = new Node(7);
   //
   Node g = new Node(4);
   Node h = new Node(1);
   Node i = new Node(0);
   Node j = new Node(8);
   // 10 nodes
   a.Left = b;
   a.Right = g;
   b.Left = c;
   c.Right = d;
   d.Left = e;
   d.Right = f;
   g.Left = h;
   g.Right = i;
   i.Left = j;
   int[] nodes = getColumnOrder(a,10);
   for(int idx = 0; idx < 10; idx++){
    Console.Write("{0}, ",nodes[idx]);
   }
 
  }
 private static int[] getColumnOrder(Node root, int size){
   int[] result = new int[size];
   Queue<(Node,int)> auxQueue = new Queue<(Node,int)>();
   Dictionary<int,List<int>> columnsMap =  new Dictionary<int,List<int>>();
   auxQueue.Enqueue((root,0));
   int idx = 0;
   while(auxQueue.Count != 0 ){
     (Node node, int level) current  = auxQueue.Dequeue();
     if (current.node is null){
      continue;
     }
     if (columnsMap.ContainsKey(current.level)){
      columnsMap[current.level].Add(current.node.Value);  
     }else{
      columnsMap[current.level] = new List<int>();
      columnsMap[current.level].Add(current.node.Value);
     }
     auxQueue.Enqueue((current.node.Left,current.level-1));
     auxQueue.Enqueue((current.node.Right,current.level+1));
   
   }
   foreach(KeyValuePair<int,List<int>> column in columnsMap.OrderBy(x => x.Key)  ){
     foreach(int num in column.Value){
      result[idx] = num;
      idx++;
     }
   }

   return result;

 } 

 }

}

Output: 5, 9, 3, 2, 6, 1, 7, 4, 8, 0