#591

Tag Validator

master · 1760 · lc hard +32 · verified · 40.3% accepted · 181 likes · top 20%

Description

Validate a code snippet string according to these rules:

- The entire snippet must be enclosed in a single valid closed tag of the form <TAG_NAME>TAG_CONTENT</TAG_NAME>, where both tag names must match.

- A valid TAG_NAME contains only uppercase letters and has a length between 1 and 9.

- Valid TAG_CONTENT may include other valid closed tags, CDATA sections, and arbitrary characters — but no unmatched <, no mismatched tags, and no tags with invalid names.

- Any < without a following > is considered unmatched. Everything from < (or </) up to the next > is treated as a tag name (even if invalid).

- A CDATA section has the form <![CDATA[CDATA_CONTENT]]>, where CDATA_CONTENT is everything between <![CDATA[ and the first ]]>. CDATA content is always treated as plain text, never parsed.

Example 1:

Input: code = "<DIV>This is the first line <![CDATA[<div>]]></DIV>"

Output: true

Explanation:

The code is wrapped in a closed tag : <DIV> and </DIV>.

The TAG_NAME is valid, the TAG_CONTENT consists of some characters and cdata.

Although CDATA_CONTENT has an unmatched start tag with invalid TAG_NAME, it should be considered as plain text, not parsed as a tag.

So TAG_CONTENT is valid, and then the code is valid. Thus return true.

Example 2:

Input: code = "<DIV>>> ![cdata[]] <![CDATA[<div>]>]]>]]>>]</DIV>"

Output: true

Explanation:

We first separate the code into : start_tag|tag_content|end_tag.

start_tag -> "<DIV>"

end_tag -> "</DIV>"

tag_content could also be separated into : text1|cdata|text2.

text1 -> ">> ![cdata[]] "

cdata -> "<![CDATA[<div>]>]]>", where the CDATA_CONTENT is "<div>]>"

text2 -> "]]>>]"

The reason why start_tag is NOT "<DIV>>>" is because of the rule 6.

The reason why cdata is NOT "<![CDATA[<div>]>]]>]]>" is because of the rule 7.

Example 3:

Input: code = "<A> <B> </A> </B>"

Output: false

Explanation: Unbalanced. If "<A>" is closed, then "<B>" must be unmatched, and vice versa.

Code

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class Solution:
    def isValid(self, code: str) -> bool:

class Solution:
    def isValid(self, code: str) -> bool: