### 中序遍歷-非遞歸  ~~~ // 中序遍歷，非遞歸 public static void in(TreeNode node){ Stack<TreeNode> stack = new Stack<>(); // 頭節點入棧 stack.push(node); while(!stack.isEmpty()){ // 左子數入棧 while(node.left != null){ stack.push(node.left); node = node.left; } TreeNode cur = stack.pop(); System.out.print(cur.val+"->"); // 如果有右，則右節點入棧 if(null != cur.right){ stack.push(cur.right); // 將node指針指向右節點 node = cur.right; } } } ~~~ ``` 中序遍歷:(非遞歸) 4->2->5->1->6->3->7-> ```