remove-duplicate-letters

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Algorithms

Given a string <code>s</code>, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical order among all possible results.

&nbsp;
Example 1:

<pre>
Input: s = &quot;bcabc&quot;
Output: &quot;abc&quot;
</pre>

Example 2:

<pre>
Input: s = &quot;cbacdcbc&quot;
Output: &quot;acdb&quot;
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= s.length &lt;= 104</code></li>
	<li><code>s</code> consists of lowercase English letters.</li>
</ul>

&nbsp;
Note: This question is the same as 1081: <a href="https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/" target="_blank">https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/</a>

removeDuplicateLetters

Remove Duplicate Letters

Smallest K-Length Subsequence With Occurrences of a Letter

smallest-k-length-subsequence-with-occurrences-of-a-letter

含特定字母的最小子序列

Stack

Greedy

String

Monotonic Stack

给你一个字符串 <code>s</code> ，请你去除字符串中重复的字母，使得每个字母只出现一次。需保证 返回结果的字典序最小（要求不能打乱其他字符的相对位置）。

&nbsp;

示例 1：

<pre>
输入：<code>s = "bcabc"</code>
输出<code>：</code><code>"abc"</code>
</pre>

示例 2：

<pre>
输入：<code>s = "cbacdcbc"</code>
输出：<code>"acdb"</code></pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= s.length &lt;= 104</code></li>
	<li><code>s</code> 由小写英文字母组成</li>
</ul>

&nbsp;

注意：该题与 1081 <a href="https://leetcode-cn.com/problems/smallest-subsequence-of-distinct-characters">https://leetcode-cn.com/problems/smallest-subsequence-of-distinct-characters</a> 相同