leetcode-problemset/leetcode-cn/problem (English)/等量移除后的字符串最小长度(English) [minimum-string-length-after-balanced-removals].html

<p>You are given a string <code>s</code> consisting only of the characters <code>&#39;a&#39;</code> and <code>&#39;b&#39;</code>.</p>

<p>You are allowed to repeatedly remove <strong>any <span data-keyword="substring-nonempty">substring</span></strong> where the number of <code>&#39;a&#39;</code> characters is equal to the number of <code>&#39;b&#39;</code> characters. After each removal, the remaining parts of the string are concatenated together without gaps.</p>

<p>Return an integer denoting the <strong>minimum possible length</strong> of the string after performing any number of such operations.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = <code>&quot;aabbab&quot;</code></span></p>

<p><strong>Output:</strong> <span class="example-io">0</span></p>

<p><strong>Explanation:</strong></p>

<p>The substring <code>&quot;aabbab&quot;</code> has three <code>&#39;a&#39;</code> and three <code>&#39;b&#39;</code>. Since their counts are equal, we can remove the entire string directly. The minimum length is 0.</p>
</div>

<p><strong class="example">Example 2:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = <code>&quot;aaaa&quot;</code></span></p>

<p><strong>Output:</strong> <span class="example-io">4</span></p>

<p><strong>Explanation:</strong></p>

<p>Every substring of <code>&quot;aaaa&quot;</code> contains only <code>&#39;a&#39;</code> characters. No substring can be removed as a result, so the minimum length remains 4.</p>
</div>

<p><strong class="example">Example 3:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = <code>&quot;aaabb&quot;</code></span></p>

<p><strong>Output:</strong> <span class="example-io">1</span></p>

<p><strong>Explanation:</strong></p>

<p>First, remove the substring <code>&quot;ab&quot;</code>, leaving <code>&quot;aab&quot;</code>. Next, remove the new substring <code>&quot;ab&quot;</code>, leaving <code>&quot;a&quot;</code>. No further removals are possible, so the minimum length is 1.</p>
</div>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
	<li><code>s[i]</code> is either <code>&#39;a&#39;</code> or <code>&#39;b&#39;</code>.</li>
</ul>