Бинарное дерево: как я могу реализовать LCA с одним узлом?

Я пытаюсь сделать это прямо сейчас, используя рекурсию, но мне трудно, я думаю, что у меня есть логическая ошибка.

пожалуйста, помогите мне кто-нибудь Т_Т

Вот мой код до сих пор

    import java.util.ArrayList;
    public class BTNode{
        private BTNode root, left,right;
        private int item;

    public BTNode(int item){
        this(item,null,null,null);
    }
    public BTNode(int item, BTNode left, BTNode right, BTNode root,int count){
        this.item = item;
        this.left = left;
        this.right = right;
        this.root = root;
      this.count=count;
    }
    public void build(){
        this.left = new BTNode(40);
        this.left.root = this;

        this.right = new BTNode(100);
        this.right.root = this;

        this.left.right = new BTNode(45);
        this.left.right.root = this.left;

        this.left.left = new BTNode(25);
        this.left.left.root = this.left;

        this.right.left = new BTNode(70);
        this.right.left.root = this.right;

        this.right.right = new BTNode(200);
        this.right.right.root = this.right;

    }
    public void inorder(){//recursion
        //traverse the left
        if(left != null)
            left.inorder();
        //visit the root do the item
        System.out.print(this.item+" ");
        //traverse the right
        if(right != null)
            right.inorder();
    }
    public String inToString(){
        return ((left == null)?"": left.inToString()) + item + " " + ((right == null)?"": right.inToString()+" ");
    }
    //preorder()
    public void  preorder(){

      //visit the root do the item
        System.out.print(this.item+" ");
      //traverse the left
        if(left != null)
            left.preorder();
        //traverse the right
        if(right != null)
            right.preorder();
    }
   //preToString()
    public String preToString(){
        return item+ " "+((left == null)?"": left.preToString())+ ((right == null)?"": right.preToString()+" ");
    }
    //postorder()
   public void  postorder(){
        //traverse the left
        if(left != null)
            left.postorder();
        //traverse the right
        if(right != null)
            right.postorder();
      //visit root do the item
      System.out.print(this.item+" ");

    }
   //postToString()
    public String postToString(){
        return ((left == null)?"": left.postToString()) + ((right == null)?"": right.postToString()+" ")+item+ " ";
    }



    //findsum-recursive
   public int findsum(){
      //traverse left,if null traverse to right then add the two item lastly add to the root
       return ((left == null)?0: left.findsum()) + ((right == null)?0: right.findsum())+item;
   }




    //findlevel-recursive
   public int findlevel(){
      //check left && right if it is not null then iterate method recursively
      if (left == null)
                return 0;
      else if(right == null)
            return 0;
      else
          return 1 + left.findlevel();
  }
  /*
    //ancestor-recursive
   public BTNode ancestor(int value){
      if(left.count== 2){//check the root
         return left.ancestor();//traverse left node
      }
      System.out.print(item+" ");//print item if the left turns false
      if(root != null){
         right.ancestor();//traverse right node
      }
   }*/



   public int count(){
      //check if left || right are null then return 0, otherwise method were recursively executed
      return (((left==null)?0:1+left.count())+((right==null)?0:1+right.count()));
   }

   public void reference(){
      //check left != null print the root, traverse left, traverse right
      if(left != null)
         left.reference();
      if(left != null)
         System.out.print(item+" ");
      if(right != null)
         right.reference();

   }
   public void sort(){

   }
   public void insert(int given){
      BTNode node = new BTNode(given);

      if(item == 0)
         root = node;
      else
         {
            BTNode current = root; //points to the current Node
            BTNode parent; //points to the parent Node

            while(current != null)
            {
               if(item > given)
               {
                  parent = current;
                  current = left;
               }

               if(item < given)
               {
                  parent = current;
                  current = right;
               }
            }
            current = node;
            if(item < given)
               right = node;
            else
               left = node;
         }
        right.inorder();
   }
   public boolean contains(int given){
         return ((left==null)?false:left.contains(given))|| item==given || ((right == null)?false : right.contains(given));
         /*if(left != null)
            left.contains(given);
         if(right != null)
            right.contains(given);
         return item == given;*/
   }
    public static void main(String[]args){
        BTNode root = new BTNode(50);

        root.build();
        System.out.print("\nGiven :"+root.inToString());
        System.out.println("\ninorder");
        root.inorder();
        System.out.println("\npreorder");
        root.preorder();
      System.out.println("\npostorder");
        root.postorder();
      System.out.println("\nfindsum");
      System.out.println(root.findsum());
      System.out.println("\nfindlevel");
      //System.out.println(root.findlevel(200));
      System.out.println(root.findlevel());
      System.out.println("\nancestor");
      //System.out.println(root.ancestor());
      root.ancestor();
      System.out.println("\ncount");
      System.out.println(root.count());

      System.out.println("\nreference");
      //System.out.println(root.reference());
      root.reference();
      System.out.println("\nsort");
      //System.out.print(root.sort());
      root.sort();
      System.out.println("\nContains");
      System.out.println(root.contains(new Integer(70)));
      System.out.println("\ninsert");
      //System.out.print(root.sort());
      root.insert(new Integer(71));
          root.printinorder();
   }
}

Пожалуйста, также проверьте мой механизм вставки... Я не думаю, что это правильный способ сделать это