minimum-length-of-string-after-operations

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Algorithms

You are given a string <code>s</code>.

You can perform the following process on <code>s</code> any number of times:

<ul>
	<li>Choose an index <code>i</code> in the string such that there is at least one character to the left of index <code>i</code> that is equal to <code>s[i]</code>, and at least one character to the right that is also equal to <code>s[i]</code>.</li>
	<li>Delete the closest occurrence of <code>s[i]</code> located to the left of <code>i</code>.</li>
	<li>Delete the closest occurrence of <code>s[i]</code> located to the right of <code>i</code>.</li>
</ul>

Return the minimum length of the final string <code>s</code> that you can achieve.

&nbsp;
Example 1:

<div class="example-block">
Input: s = &quot;abaacbcbb&quot;

Output: 5

Explanation: 
We do the following operations:

<ul>
	<li>Choose index 2, then remove the characters at indices 0 and 3. The resulting string is <code>s = &quot;bacbcbb&quot;</code>.</li>
	<li>Choose index 3, then remove the characters at indices 0 and 5. The resulting string is <code>s = &quot;acbcb&quot;</code>.</li>
</ul>
</div>

Example 2:

<div class="example-block">
Input: s = &quot;aa&quot;

Output: 2

Explanation: 
We cannot perform any operations, so we return the length of the original string.
</div>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= s.length &lt;= 2 * 105</code></li>
	<li><code>s</code> consists only of lowercase English letters.</li>
</ul>

minimumLength

Minimum Length of String After Operations

Hash Table

String

Counting

给你一个字符串&nbsp;<code>s</code>&nbsp;。

你需要对 <code>s</code>&nbsp;执行以下操作 任意&nbsp;次：

<ul>
	<li>选择一个下标 <code>i</code>&nbsp;，满足 <code>s[i]</code>&nbsp;左边和右边都&nbsp;至少&nbsp;有一个字符与它相同。</li>
	<li>删除 <code>i</code>&nbsp;左边&nbsp;离它 最近&nbsp;的&nbsp;<code>s[i]</code> 字符。</li>
	<li>删除 <code>i</code>&nbsp;右边&nbsp;离它 最近&nbsp;的&nbsp;<code>s[i]</code> 字符。</li>
</ul>

请你返回执行完所有操作后， <code>s</code>&nbsp;的 最短&nbsp;长度。

&nbsp;

示例 1：

<div class="example-block">
输入：s = "abaacbcbb"

输出：5

解释： 
我们执行以下操作：

<ul>
	<li>选择下标 2 ，然后删除下标 0 和 3 处的字符，得到&nbsp;<code>s = "bacbcbb"</code>&nbsp;。</li>
	<li>选择下标 3 ，然后删除下标 0 和 5 处的字符，得到&nbsp;<code>s = "acbcb"</code>&nbsp;。</li>
</ul>
</div>

示例 2：

<div class="example-block">
输入：s = "aa"

输出：2

解释： 
无法对字符串进行任何操作，所以返回初始字符串的长度。
</div>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= s.length &lt;= 2 * 105</code></li>
	<li><code>s</code>&nbsp;只包含小写英文字母。</li>
</ul>