Recursive traversals of a binary tree.

TreeTraversalRecursive.cs

public class TreeNode<T> where T : IComparable<T>
{
  public T Value { get; set; }
  public TreeNode<T> Left { get; set; }
  public TreeNode<T> Right { get; set; }
  public TreeNode<T> Parent { get; set; }
}

public static class TreeTraversalRecursive
{
  public static void PreOrderTraversal<T>(TreeNode<T> root, Action<T> action) where T : IComparable<T>
  {
    if(root == null)
      return;
    
    action(root.Value);
    PreOrderTraversal<T>(root.Left, action);
    PreOrderTraversal<T>(root.Right, action);
  }
  
  public static void InOrderTraversal<T>(TreeNode<T> root, Action<T> action) where T : IComparable<T>
  {
    if(root == null)
      return;
    
    InOrderTraversal<T>(root.Left, action);
    action(root.Value);
    InOrderTraversal<T>(root.Right, action);
  }
  
  public static void PostOrderTraversal<T>(TreeNode<T> root, Action<T> action) where T : IComparable<T>
  {
    if(root == null)
      return;
    
    PostOrderTraversal<T>(root.Left, action);
    PostOrderTraversal<T>(root.Right, action);
    action(root.Value);
  }
}