2019年9月8日秋季PAT甲级题解--3 Postfix Expression (25 分) 暗含玄机

最新推荐文章于 2021-03-11 00:55:07 发布

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最新推荐文章于 2021-03-11 00:55:07 发布 · 1.5k 阅读

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该博客详细介绍了如何将给定的二叉语法树转换为后缀表达式，强调了从节点编号构建树以及利用深度优先搜索（DFS）策略进行转换的方法。内容包括输入输出规格说明、样例输入输出以及问题分析和满分代码示例。

Given a syntax tree (binary), you are supposed to output the corresponding postfix expression, with parentheses reflecting the precedences of the operators.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤ 20) which is the total number of nodes in the syntax tree. Then N lines follow, each gives the information of a node (the i-th line corresponds to the i-th node) in the format:

data left_child right_child

where data is a string of no more than 10 characters, left_child and right_child are the indices of this node's left and right children, respectively. The nodes are indexed from 1 to N. The NULL link is represented by −1. The figures 1 and 2 correspond to the samples 1 and 2, respectively.