update: add traversePostOrder

BinaryTree.java

@@ -7,6 +7,10 @@ public class BinaryTree {
     insert(content);
   }
 
+  public Node getRoot() {
+    return rootNode;
+  }
+
   public boolean search(int value) {
      if (rootNode == null) {
        return false;
@@ -120,6 +124,14 @@ public class BinaryTree {
     }
   }
 
+  public void traversePostOrder(Node node) {
+    if (node != null) {
+      traversePostOrder(node.getLeftNode());
+      traversePostOrder(node.getRightNode());
+      System.out.print(" " + node.getContent());
+    }
+  }
+
   // Print functions from https://www.baeldung.com/java-print-binary-tree-diagram
   // public void print() {
   //   StringBuilder sb = new StringBuilder();