Largest smaller BST key - mock interview 11:29 PM

LargestSmallerBSTKey.cs

1using System;

class Solution
{
  public class Node
  {
    public int key;
    public Node left;
    public Node right;
    public Node parent;
  }
    
  public static int findLargestSmallerKey(Node rootNode, int num)  // given 17, find 14
  {
    if(rootNode == null) // false 
    {
      return -1; 
    }
    
    var visitNode = rootNode; // 20 
    var largestSmaller = -1;  
    
    while(visitNode != null) // true
    {
      if (visitNode.key < num) // 20 < 17 false, 9 < 17 , 12 < 17 , 14 < 17
      {
        largestSmaller = visitNode.key; // 8 , 12, 14
      
        visitNode = visitNode.right; // node 12, node 14, null 
      }
      else 
      {
        visitNode = visitNode.left; // node 9
      }
    }
    
    return largstSmaller; // n14
  }

  static void Main(string[] args)
  {

  }
}

/*

14 --> 12
5 9 11 12 14 20 25 
              |
              
             given 17, find larest smaller BST key
          14
          left side -> 
          20 > 17
   |       
   9  < 17 , 9 largest, I am not sure 
   
   go to right 
     |
     12 < 17 
     
        14 < 17 
        
        14.right == null -> largest one is 14
        
        
*/