feat: add weekly contest 389 (#2452)

Author: yanglbme

solution/3000-3099/3083.Existence of a Substring in a String and Its Reverse/README.md

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+# [3083. 字符串及其反转中是否存在同一子字符串](https://leetcode.cn/problems/existence-of-a-substring-in-a-string-and-its-reverse)
+
+[English Version](/solution/3000-3099/3083.Existence%20of%20a%20Substring%20in%20a%20String%20and%20Its%20Reverse/README_EN.md)
+
+<!-- tags: -->
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>给你一个字符串 <code>s</code> ，请你判断字符串 <code>s</code> 是否存在一个长度为 <code>2</code> 的子字符串，在其反转后的字符串中也出现。</p>
+
+<p>如果存在这样的子字符串，返回 <code>true</code>；如果不存在，返回 <code>false</code> 。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "leetcode"</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">true</span></p>
+
+<p><strong>解释：</strong>子字符串 <code>"ee"</code> 的长度为 <code>2</code>，它也出现在 <code>reverse(s) == "edocteel"</code> 中。</p>
+</div>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "abcba"</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">true</span></p>
+
+<p><strong>解释：</strong>所有长度为 <code>2</code> 的子字符串 <code>"ab"</code>、<code>"bc"</code>、<code>"cb"</code>、<code>"ba"</code> 也都出现在 <code>reverse(s) == "abcba"</code> 中。</p>
+</div>
+
+<p><strong class="example">示例 3：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "abcd"</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">false</span></p>
+
+<p><strong>解释：</strong>字符串 <code>s</code> 中不存在满足「在其反转后的字符串中也出现」且长度为 <code>2</code> 的子字符串。</p>
+</div>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 100</code></li>
+	<li>字符串 <code>s</code> 仅由小写英文字母组成。</li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3083.Existence of a Substring in a String and Its Reverse/README_EN.md

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+# [3083. Existence of a Substring in a String and Its Reverse](https://leetcode.com/problems/existence-of-a-substring-in-a-string-and-its-reverse)
+
+[中文文档](/solution/3000-3099/3083.Existence%20of%20a%20Substring%20in%20a%20String%20and%20Its%20Reverse/README.md)
+
+<!-- tags: -->
+
+## Description
+
+<p>Given a<strong> </strong>string <code>s</code>, find any <span data-keyword="substring">substring</span> of length <code>2</code> which is also present in the reverse of <code>s</code>.</p>
+
+<p>Return <code>true</code><em> if such a substring exists, and </em><code>false</code><em> otherwise.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = &quot;leetcode&quot;</span></p>
+
+<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">true</span></p>
+
+<p><strong>Explanation:</strong> Substring <code>&quot;ee&quot;</code> is of length <code>2</code> which is also present in <code>reverse(s) == &quot;edocteel&quot;</code>.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = &quot;abcba&quot;</span></p>
+
+<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">true</span></p>
+
+<p><strong>Explanation:</strong> All of the substrings of length <code>2</code> <code>&quot;ab&quot;</code>, <code>&quot;bc&quot;</code>, <code>&quot;cb&quot;</code>, <code>&quot;ba&quot;</code> are also present in <code>reverse(s) == &quot;abcba&quot;</code>.</p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = &quot;abcd&quot;</span></p>
+
+<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">false</span></p>
+
+<p><strong>Explanation:</strong> There is no substring of length <code>2</code> in <code>s</code>, which is also present in the reverse of <code>s</code>.</p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 100</code></li>
+	<li><code>s</code> consists only of lowercase English letters.</li>
+</ul>
+
+## Solutions
+
+### Solution 1
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3084.Count Substrings Starting and Ending with Given Character/README.md

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+# [3084. 统计以给定字符开头和结尾的子字符串总数](https://leetcode.cn/problems/count-substrings-starting-and-ending-with-given-character)
+
+[English Version](/solution/3000-3099/3084.Count%20Substrings%20Starting%20and%20Ending%20with%20Given%20Character/README_EN.md)
+
+<!-- tags: -->
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>给你一个字符串 <code>s</code> 和一个字符 <code>c </code>。返回在字符串 <code>s</code> 中并且以 <code>c</code> 字符开头和结尾的<span data-keyword="substring-nonempty">非空子字符串</span>的总数。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "abada", c = "a"</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
+
+<p><strong>解释：</strong>以 <code>"a"</code> 开头和结尾的子字符串有： <code>"<strong><u>a</u></strong>bada"</code>、<code>"<u><strong>aba</strong></u>da"</code>、<code>"<u><strong>abada</strong></u>"</code>、<code>"ab<u><strong>a</strong></u>da"</code>、<code>"ab<u><strong>ada</strong></u>"</code>、<code>"abad<u><strong>a</strong></u>"</code>。</p>
+</div>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "zzz", c = "z"</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
+
+<p><strong>解释：</strong>字符串 <code>s</code> 中总共有 <code>6</code> 个子字符串，并且它们都以 <code>"z"</code> 开头和结尾。</p>
+</div>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>s</code> 和 <code>c</code> 均由小写英文字母组成。</li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3084.Count Substrings Starting and Ending with Given Character/README_EN.md

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+# [3084. Count Substrings Starting and Ending with Given Character](https://leetcode.com/problems/count-substrings-starting-and-ending-with-given-character)
+
+[中文文档](/solution/3000-3099/3084.Count%20Substrings%20Starting%20and%20Ending%20with%20Given%20Character/README.md)
+
+<!-- tags: -->
+
+## Description
+
+<p>You are given a string <code>s</code> and a character <code>c</code>. Return <em>the total number of <span data-keyword="substring-nonempty">substrings</span> of </em><code>s</code><em> that start and end with </em><code>c</code><em>.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = &quot;abada&quot;, c = &quot;a&quot;</span></p>
+
+<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
+
+<p><strong>Explanation:</strong> Substrings starting and ending with <code>&quot;a&quot;</code> are: <code>&quot;<strong><u>a</u></strong>bada&quot;</code>, <code>&quot;<u><strong>aba</strong></u>da&quot;</code>, <code>&quot;<u><strong>abada</strong></u>&quot;</code>, <code>&quot;ab<u><strong>a</strong></u>da&quot;</code>, <code>&quot;ab<u><strong>ada</strong></u>&quot;</code>, <code>&quot;abad<u><strong>a</strong></u>&quot;</code>.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = &quot;zzz&quot;, c = &quot;z&quot;</span></p>
+
+<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
+
+<p><strong>Explanation:</strong> There are a total of <code>6</code> substrings in <code>s</code> and all start and end with <code>&quot;z&quot;</code>.</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</code> and <code>c</code> consist&nbsp;only of lowercase English letters.</li>
+</ul>
+
+## Solutions
+
+### Solution 1
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3085.Minimum Deletions to Make String K-Special/README.md

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+# [3085. 成为 K 特殊字符串需要删除的最少字符数](https://leetcode.cn/problems/minimum-deletions-to-make-string-k-special)
+
+[English Version](/solution/3000-3099/3085.Minimum%20Deletions%20to%20Make%20String%20K-Special/README_EN.md)
+
+<!-- tags: -->
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>给你一个字符串 <code>word</code> 和一个整数 <code>k</code>。</p>
+
+<p>如果&nbsp;<code>|freq(word[i]) - freq(word[j])| &lt;= k</code> 对于字符串中所有下标 <code>i</code> 和 <code>j</code>&nbsp; 都成立，则认为 <code>word</code> 是 <strong>k 特殊字符串</strong>。</p>
+
+<p>此处，<code>freq(x)</code> 表示字符 <code>x</code> 在 <code>word</code> 中的<span data-keyword="frequency-letter">出现频率</span>，而 <code>|y|</code> 表示 <code>y</code> 的绝对值。</p>
+
+<p>返回使 <code>word</code> 成为 <strong>k 特殊字符串</strong> 需要删除的字符的最小数量。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">word = "aabcaba", k = 0</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">3</span></p>
+
+<p><strong>解释：</strong>可以删除 <code>2</code> 个 <code>"a"</code> 和 <code>1</code> 个 <code>"c"</code> 使 <code>word</code> 成为 <code>0</code> 特殊字符串。<code>word</code> 变为 <code>"baba"</code>，此时 <code>freq('a') == freq('b') == 2</code>。</p>
+</div>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">word = "dabdcbdcdcd", k = 2</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">2</span></p>
+
+<p><strong>解释：</strong>可以删除 <code>1</code> 个 <code>"a"</code> 和 <code>1</code> 个 <code>"d"</code> 使 <code>word</code> 成为 <code>2</code> 特殊字符串。<code>word</code> 变为 <code>"bdcbdcdcd"</code>，此时 <code>freq('b') == 2</code>，<code>freq('c') == 3</code>，<code>freq('d') == 4</code>。</p>
+</div>
+
+<p><strong class="example">示例 3：</strong></p>
+
+<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
+<p><strong>输入：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">word = "aaabaaa", k = 2</span></p>
+
+<p><strong>输出：</strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">1</span></p>
+
+<p><strong>解释：</strong>可以删除<strong> </strong>1 个 <code>"b"</code> 使 <code>word</code> 成为 <code>2</code>特殊字符串。因此，<code>word</code> 变为 <code>"aaaaaa"</code>，此时每个字母的频率都是 <code>6</code>。</p>
+</div>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= word.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>0 &lt;= k &lt;= 10<sup>5</sup></code></li>
+	<li><code>word</code> 仅由小写英文字母组成。</li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->