目录

题目

Input Specification:

Output Specification:

Sample Input:

Sample Output:

思路

代码

题目

Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, a binary tree can be uniquely determined.

Now given a sequence of statements about the structure of the resulting tree, you are supposed to tell if they are correct or not. A statment is one of the following:

• A is the root
• A and B are siblings
• A is the parent of B
• A is the left child of B
• A is the right child of B
• A and B are on the same level
• It is a full tree

Note:

• Two nodes are on the same level, means that they have the same depth.
• A full binary tree is a tree in which every node other than the leaves has two children.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤30), the total number of nodes in the binary tree. The second line gives the postorder sequence and the third line gives the inorder sequence. All the numbers in a line are no more than 103 and are separated by a space.

Then another positive integer M (≤30) is given, followed by M lines of statements. It is guaranteed that both A and B in the statements are in the tree.

Output Specification:

For each statement, print in a line Yes if it is correct, or No if not.

Sample Input:

9
16 7 11 32 28 2 23 8 15
16 23 7 32 11 2 28 15 8
7
15 is the root
8 and 2 are siblings
32 is the parent of 11
23 is the left child of 16
28 is the right child of 2
7 and 11 are on the same level
It is a full tree

Sample Output:

Yes
No
Yes
No
Yes
Yes
Yes

思路

这题也不是难题，可以在1167 Cartesian Tree 或1020 Tree Traversals的基础上对dfs函数进行改进，即在dfs函数里面统计当前子树的根节点的信息，包括：层次(level)、双亲(parent)和左右孩子(left、right)

关键技术：

1. 如何获取statement中的数字 --- --- 用正则表达式做匹配

在1164 Good in C这题中也用到了正则表达式匹配字符串，封装好的函数代码如下：

#include // 根据传入的正则表达式分割字符串
// str-即将要进行分割的字符串；sep-正则表达式；result-存放分割后结果的容器 
void splitStringByRegex(string str,string sep,vector &result){regex pattern(sep);sregex_token_iterator end;// 循环结束的标志 // 有-1时表示得到i是除正则表达式外的部分，没有-1时表示得到i是和正则表达式匹配的部分 for(sregex_token_iterator i(str.begin(),str.end(),pattern);i!=end;++i){ result.push_back(stoi(*i));}
}

2. 如何判断statement是哪一类别 --- --- 用str1.find(str2)函数

// str1中找到了str2
if(str1.find(str2)!=string::npos){... ...
}else{// 没找到时... ...
}

代码

#include 
#include 
#include 
#include 
#include