leetcode-problemset/leetcode-cn/problem (Chinese)/最长有效括号 [longest-valid-parentheses].html

<p>给你一个只包含 <code>'('</code>&nbsp;和 <code>')'</code>&nbsp;的字符串，找出最长有效（格式正确且连续）括号<span data-keyword="substring">子串</span>的长度。</p>

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<p><strong>示例 1：</strong></p>

<pre>
<strong>输入：</strong>s = "(()"
<strong>输出：</strong>2
<strong>解释：</strong>最长有效括号子串是 "()"
</pre>

<p><strong>示例 2：</strong></p>

<pre>
<strong>输入：</strong>s = ")()())"
<strong>输出：</strong>4
<strong>解释：</strong>最长有效括号子串是 "()()"
</pre>

<p><strong>示例 3：</strong></p>

<pre>
<strong>输入：</strong>s = ""
<strong>输出：</strong>0
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>0 &lt;= s.length &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>s[i]</code> 为 <code>'('</code> 或 <code>')'</code></li>
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