You need to parse these tags: <p/>, <br/>, <blockquote/>, and <del/>.
A sequence of two or more consecutive newline characters starts a new paragraph.
Other formatting commands do not cross paragraphs.
A single newline character is a soft line break, <br/>.
A blockquote is one or more consecutive lines where the first two characters on the line are > (a greater than sign followed by a space).
Text in strikethrough (<del></del>) is surrounded by a pair of tildes.
Example:
markdown_input = """This is a paragraph with a soft
line break.
This is another paragraph that has
> Some text that
> is in a
> block quote.
This is another paragraph with a ~~strikethrough~~ word."""output = """<p>This is a paragraph with a soft<br />line break.</p>
<p>This is another paragraph that has<br />
<blockquote>Some text that<br />is in a<br />block quote.</blockquote>
</p>
<p>This is another paragraph with a <del>strikethrough</del> word.</p>"""Note: It is not important to produce this specific output. We only care if the HTML is valid.
这道题要求把一段带有简单标记的 Markdown 文本转换成合法 HTML，核心是正确处理段落、软换行、引用和删除线。连续两个及以上换行表示新段落，单个换行要转换成 <code><br /></code>；以 <code>> </code> 开头的连续行要为 blockquote；而 <code>~~text~~</code> 需要输出为 <code><del>text</del></code>。实现时通常需要按行扫描并维护当前段落状态，注意这些格式规则不能跨段落生效。
