二叉树--后序遍历

• 后序遍历：左右根，从叶子结点开始

  //递归
  public static void postOrder(TreeNode root){
      if(root != null){
      	postOrder(root.lchild);
  		postOrder(root.rchild);
      	System.out.println(root.data + " ");
      }
  }
  

  //后序遍历---非递归
  public List postOrder(TreeNode root){
  	while(root!=null || !stack.isEmpty()){
  		while(root!=null){
  			list.add(root);
  			static.push(root);
  			root = root.right;
  		}
  		TreeNode node = stack.pop();
  		root = node.left;
  	}
  	Conlections.reverse(list);
  	return list;
  }