Write a method named completeToLevel that adds nodes to a binary tree of integers so that the first n levels are complete.
A level is complete if every possible node at that level is not null.
Your method accepts as its parameters a TreeNode that refers to the root of the tree, and an integer n, and returns the tree's updated root.
We will use the convention that the overall root is at level 1, it's children are at level 2, and so on.
You should preserve any existing nodes in the tree.
Any new nodes added to the tree should have -1 as their data.
For example, suppose a variable called tree refers to the root of the following tree:
(17 (83 (19 / (48))) (6 / (87 (75))))
The call of completeToLevel(tree, 3) should return the root of the tree with the following updated state:
(17 (83 (19 / (48)) (-1)) (6 (-1) (87 (75))))
In this case, the request was to fill in nodes as necessary to ensure that the first 3 levels are complete.
There were two nodes missing at level 3.
Notice that level 4 of this tree is not complete because the call requested that nodes be filled in to level 3 only.
You may assume that the level passed will be at least 1.
Assume that you are interacting with TreeNodes as defined below:
public class TreeNode {
public int data;
public TreeNode left;
public TreeNode right;
public TreeNode() { ... }
public TreeNode(int data) { ... }
public TreeNode(int data, TreeNode left, TreeNode right) { ... }
}
