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Tree Traversals Again

时间:2019-04-16 01:28:53      阅读:73      评论:0      收藏:0      [点我收藏+]

标签:堆栈   输入   com   out   uniq   sep   使用   gen   lines   

An inorder binary tree traversal can be implemented in a non-recursive way with a stack. For example, suppose that when a 6-node binary tree (with the keys numbered from 1 to 6) is traversed, the stack operations are: push(1); push(2); push(3); pop(); pop(); push(4); pop(); pop(); push(5); push(6); pop(); pop(). Then a unique binary tree (shown in Figure 1) can be generated from this sequence of operations. Your task is to give the postorder traversal sequence of this tree.

技术图片
Figure 1

Input Specification:

Each input file contains one test case. For each case, the first line contains a positive integer N (≤) which is the total number of nodes in a tree (and hence the nodes are numbered from 1 to N). Then 2 lines follow, each describes a stack operation in the format: "Push X" where X is the index of the node being pushed onto the stack; or "Pop" meaning to pop one node from the stack.

Output Specification:

For each test case, print the postorder traversal sequence of the corresponding tree in one line. A solution is guaranteed to exist. All the numbers must be separated by exactly one space, and there must be no extra space at the end of the line.

Sample Input:

6
Push 1
Push 2
Push 3
Pop
Pop
Push 4
Pop
Pop
Push 5
Push 6
Pop
Pop

Sample Output:

3 4 2 6 5 1

 

可以使用堆栈以非递归方式实现顺序二进制树遍历。你的任务是给出这棵树的后序遍历序列。

每个输入文件包含一个测试用例。对于每种情况,第一行包含正整数N≤ 0),它是节点的总数量在树(并且因此节点编号从1到N)。然后接下来是N行,每行描述一种堆栈操作,格式为:“Push X”,其中X是被推入堆栈的节点的索引; 或“Pop”表示从堆栈中弹出一个节点。

对于每个测试用例,在一行中打印相应树的后序遍历序列。保证存在解决方案。所有数字必须用一个空格分隔,并且在行的末尾不能有额外的空格。

 

今天先看看题,明天再写。。

 

Tree Traversals Again

标签:堆栈   输入   com   out   uniq   sep   使用   gen   lines   

原文地址:https://www.cnblogs.com/jiamian/p/10714354.html

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