public class Solution extends Object
591 - Tag Validator.
Hard
Given a string representing a code snippet, 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:
<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.TAG_NAME only contain upper-case letters , and has length in range [1,9]. Otherwise, the TAG_NAME is invalid.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.< 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).<![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.Example 1:
Input: code = “
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 = “
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:
Output: false
Explanation: Unbalanced. If “” is closed, then “” must be unmatched, and vice versa.
Constraints:
1 <= code.length <= 500code consists of English letters, digits, '<', '>', '/', '!', '[', ']', '.', and ' '.| Constructor and Description |
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Solution() |
public boolean isValid(String code)
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