### 前序遍历-非递归  ~~~ // 前序遍历，非递归 public static void pre(TreeNode node){ Stack<TreeNode> stack = new Stack<>(); // 头节点入栈 stack.push(node); while(!stack.isEmpty()){ TreeNode cur = stack.pop(); System.out.print(cur.val+"->"); // 先压右，再压左 if(null != cur.right){ stack.push(cur.right); } if(null != cur.left){ stack.push(cur.left); } } } ~~~ ``` 前序遍历:(非递归) 1->2->4->5->3->6->7-> ```