我们随便点进一个discuz论坛，在地址后面加?1，有的论坛就会显示uid=1的用户资料页（或是家园空间首页，取决于这个论坛有没有开通家园）：

Given preorder and inorder traversal of a tree, construct the binary tree. 根据前序和中序遍历序列构建二叉树。 Note: You may assume that duplicates do not exist in the tree.

Given inorder and postorder traversal of a tree, construct the binary tree.

重点看“根”的位置，在最前面就是前序，中间就是中序，后面就是后序。补充一点，上述排列都是DFT（深度优先排列，Depth First Traversals）。另有Breadth First or Level Order Traversal 。...

Given a binary tree, return the preorder traversal of its nodes’ values.

Given a binary tree, return the postorder traversal of its nodes’ values.

Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).

Given a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate ...

Given preorder and inorder traversal of a tree, construct the binary tree.

Given inorder and postorder traversal of a tree, construct the binary tree.