<p>有重复字符串的排列组合。编写一种方法，计算某字符串的所有排列组合。</p>

<p><strong>示例1:</strong></p>

<pre><strong> 输入</strong>：S = &quot;qqe&quot;
<strong> 输出</strong>：[&quot;eqq&quot;,&quot;qeq&quot;,&quot;qqe&quot;]
</pre>

<p><strong>示例2:</strong></p>

<pre><strong> 输入</strong>：S = &quot;ab&quot;
<strong> 输出</strong>：[&quot;ab&quot;, &quot;ba&quot;]
</pre>

<p><strong>提示:</strong></p>

<ol>
	<li>字符都是英文字母。</li>
	<li>字符串长度在[1, 9]之间。</li>
</ol>
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