bst-traverse-tree.java

public class Solution {
  public void traverse(TreeNode root) {
    Queue<TreeNode> nodes = new ArrayList();
    nodes.add(root);
    while (!nodes.isEmpty()) {
      TreeNode node = nodes.remove();
      
      System.out.println(node.val);
      
      if (node.left != null) queue.add(node.left);
      if (node.right != null) queue.add(node.right);
    }
  }
}