Binary Search Tree Longest Path

LongestPath.java

/*
Interview Question: 
Here's a binary tree: find the longest path within it. 
So, find a path between any two leaf nodes, where the path is the longest.” 
*/

public class TreeNode{
  int data;
  TreeNode left;
  TreeNode right;
  
  TreeNode(int d){
    data = d;
    left = null;
    right = null;
  }
}

public class BinarySearchTree{
  TreeNode root;
  
  public int getLongestPath(TreeNode root){
    if (root == null){
      return 0;
    }
    else if (root.left == null && root.right != null){
      //longest path is from root
      return getLongestPathHelper(root.right, 1);
    }
    else if (root.left != null && root.right == null){
      //longest path is from root
      return getLongestPathHelper(root.left, 1);
    }
    else{
      //longest path is between deepest node on the left side and deepest node on the right side
      return (getLongestPathHelper(root.left, 1) + getLongestPathHelper(root.right, 1));
    }
    
  }
  
  public int getLongestPathHelper(TreeNode node, int level){
    
    if (node.left == null && node.right == null){
      return level;
    }
    else{
      
      if (root.left == null && root.right != null){
        return getLongestPathHelper(root.right, level + 1);
      }
      else if (root.left != null && root.right == null){
        return getLongestPathHelper(root.left, level + 1);
      }
      else{
        int left = getLongestPathHelper(root.left, level + 1);
        int right = getLongestPathHelper(root.right, level + 1);
        return (right > left ? right : left)
      }
    }
  }
}