permutation-ii-lcci

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LCCI

Write a method to compute all permutations of a string whose characters are not necessarily unique. The list of permutations should not have duplicates.

Example1:

<pre>
 Input: S = &quot;qqe&quot;
 Output: [&quot;eqq&quot;,&quot;qeq&quot;,&quot;qqe&quot;]
</pre>

Example2:

<pre>
 Input: S = &quot;ab&quot;
 Output: [&quot;ab&quot;, &quot;ba&quot;]
</pre>

Note:

<ol>
	<li>All characters are English letters.</li>
	<li><code>1 &lt;= S.length &lt;= 9</code></li>
</ol>

Permutation II LCCI

String

Backtracking

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。

示例 1：

<pre>
 输入：S = "qqe"
 输出：["eqq","qeq","qqe"]
</pre>

示例 2：

<pre>
 输入：S = "ab"
 输出：["ab", "ba"]
</pre>

提示:

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