leetcode 591. Tag Validator标签验证器 + 解析HTML + 正则表达式

亦凉 2022-06-03 05:00 149阅读 0赞

Given a string representing a code snippet, you need to implement a tag validator to parse the code and return whether it is valid. A code snippet is valid if all the following rules hold:

The code must be wrapped in a valid closed tag. Otherwise, the code is invalid.
    A closed tag (not necessarily valid) has exactly the following format : <TAG_NAME>TAG_CONTENT</TAG_NAME>. Among them, <TAG_NAME> is the start tag, and </TAG_NAME> is the end tag. The TAG_NAME in start and end tags should be the same. A closed tag is valid if and only if the TAG_NAME and TAG_CONTENT are valid.
    A valid TAG_NAME only contain upper-case letters, and has length in range [1,9]. Otherwise, the TAG_NAME is invalid.
    A valid TAG_CONTENT may contain other valid closed tags, cdata and any characters (see note1) EXCEPT unmatched <, unmatched start and end tag, and unmatched or closed tags with invalid TAG_NAME. Otherwise, the TAG_CONTENT is invalid.
    A start tag is unmatched if no end tag exists with the same TAG_NAME, and vice versa. However, you also need to consider the issue of unbalanced when tags are nested.
    A < is unmatched if you cannot find a subsequent >. And when you find a < or </, all the subsequent characters until the next > should be parsed as TAG_NAME (not necessarily valid).
    The cdata has the following format : <![CDATA[CDATA_CONTENT]]>. The range of CDATA_CONTENT is defined as the characters between <![CDATA[ and the first subsequent ]]>.
    CDATA_CONTENT may contain any characters. The function of cdata is to forbid the validator to parse CDATA_CONTENT, so even it has some characters that can be parsed as tag (no matter valid or invalid), you should treat it as regular characters.

本题的题意就是解析HTML的标签代码，最好的方法就是使用正则表达式来做，这个很简洁，但是不会做，这个是网上参考的答案

参考的链接是[\[LeetCode\] Tag Validator 标签验证器][LeetCode_ Tag Validator]

代码如下：

#include <iostream>
    #include <vector>
    #include <map>
    #include <set>
    #include <queue>
    #include <stack>
    #include <string>
    #include <climits>
    #include <algorithm>
    #include <sstream>
    #include <functional>
    #include <bitset>
    #include <numeric>
    #include <cmath>
    #include <regex>
    
    using namespace std;
    
    class Solution 
    {
    public:
        bool isValid(string code) 
        {
            // inspired by stefanpochmann
            regex cdata("<!\\[CDATA\\[.*?\\]\\]>"), tag("<([A-Z]{1,9})>[^<]*</\\1>");
            code = regex_replace(code, cdata, "c");
            string pre = code;
            while (pre != (code = regex_replace(code, tag, "t"))) 
                pre = code;
            return "t" == code;
        }
    };

[LeetCode_ Tag Validator]: http://www.cnblogs.com/grandyang/p/7016476.html