[GeeksForGeeks] Remove all half nodes of a given binary tree

 1 public class RemoveHalfNodes {
 2     public static TreeNode removeHalfNodes(TreeNode root) {
 3         if(root == null) {
 4             return root;
 5         }
 6         root.left = removeHalfNodes(root.left);
 7         root.right = removeHalfNodes(root.right);
 8         if(root.left == null && root.right != null) {
 9             return root.right;
10         }
11         else if(root.left != null && root.right == null) {
12             return root.left;
13         }
14         return root;
15     }
16     private static void traverseTree(TreeNode root) {
17         if(root == null) {
18             return;
19         }
20         String leftVal = root.left == null ? "null" : String.valueOf(root.left.val);
21         String rightVal = root.right == null ? "null" : String.valueOf(root.right.val);
22         System.out.println(root.val + " left node: " + leftVal + "; right node: " + rightVal);
23         traverseTree(root.left);
24         traverseTree(root.right);
25     }
26     public static void main(String[] args) {
27         TreeNode[] nodes = new TreeNode[8];
28         for(int i = 0; i < 8; i++) {
29             nodes[i] = new TreeNode(i);
30         }
31         nodes[0].left = nodes[1]; nodes[0].right = nodes[2];
32         nodes[1].right = nodes[3];
33         nodes[2].right = nodes[4];
34         nodes[3].left = nodes[5]; nodes[3].right = nodes[6];
35         nodes[4].left = nodes[7];
36         TreeNode root = removeHalfNodes(nodes[0]);
37         traverseTree(root);
38     }
39 }