### 后續遍歷-非遞歸  ~~~ // 后序遍歷，非遞歸 public static void back(TreeNode node){ Stack<TreeNode> stack = new Stack<>(); Stack<TreeNode> collect = new Stack<>(); // 頭節點入棧 stack.push(node); while(!stack.isEmpty()){ TreeNode cur = stack.pop(); // 彈出的元素放到收集棧內 collect.push(cur); // 先壓左再壓右 if(null != cur.left){ stack.push(cur.left); } if(null != cur.right){ stack.push(cur.right); } } // 最后彈出收集棧里的節點 while(!collect.isEmpty()){ System.out.print(collect.pop().val+"->"); } } ~~~ ``` 中序遍歷:(非遞歸) 4->5->2->6->7->3->1-> ```