Compute the right sibling tree

ComputeRightSiblingTree.java

/**
 * Problem: Compute the right sibling tree
 */
public class ComputeRightSiblingTree {

    public void constructRightSibling(BinaryTreeNode<String> treeNode){
        BinaryTreeNode<String> leftStart = treeNode;

        while(leftStart != null && leftStart.left != null){
            populateLowerLevelNextField(leftStart);
            leftStart = leftStart.left;
        }
    }

    private void populateLowerLevelNextField(BinaryTreeNode<String> startNode){

        BinaryTreeNode<String> iter = startNode;
        while(iter != null){
            iter.left.rightSibling = iter.right;
            if(iter.rightSibling != null){
                iter.right.rightSibling = iter.rightSibling.left;
            }
            iter = iter.rightSibling;
        }
    }


   
}