feat: add solutions to lc problems: No.2820~2823

solution/2800-2899/2819.Minimum Relative Loss After Buying Chocolates/README.md

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+# [2819. Minimum Relative Loss After Buying Chocolates](https://leetcode.cn/problems/minimum-relative-loss-after-buying-chocolates)
+
+[English Version](/solution/2800-2899/2819.Minimum%20Relative%20Loss%20After%20Buying%20Chocolates/README_EN.md)
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>You are given an integer array <code>prices</code>, which shows the chocolate prices and a 2D integer array <code>queries</code>, where <code>queries[i] = [k<sub>i</sub>, m<sub>i</sub>]</code>.</p>
+
+<p>Alice and Bob went to buy some chocolates, and Alice suggested a way to pay for them, and Bob agreed.</p>
+
+<p>The terms for each query are as follows:</p>
+
+<ul>
+	<li>If the price of a chocolate is <strong>less than or equal to</strong> <code>k<sub>i</sub></code>, Bob pays for it.</li>
+	<li>Otherwise, Bob pays <code>k<sub>i</sub></code> of it, and Alice pays the <strong>rest</strong>.</li>
+</ul>
+
+<p>Bob wants to select <strong>exactly</strong> <code>m<sub>i</sub></code> chocolates such that his <strong>relative loss</strong> is <strong>minimized</strong>, more formally, if, in total, Alice has paid <code>a<sub>i</sub></code> and Bob has paid <code>b<sub>i</sub></code>, Bob wants to minimize <code>b<sub>i</sub> - a<sub>i</sub></code>.</p>
+
+<p>Return <em>an integer array</em> <code>ans</code> <em>where</em> <code>ans[i]</code> <em>is Bob&#39;s <strong>minimum relative loss </strong>possible for</em> <code>queries[i]</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [1,9,22,10,19], queries = [[18,4],[5,2]]
+<strong>Output:</strong> [34,-21]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolates with prices [1,9,10,22]. He pays 1 + 9 + 10 + 18 = 38 and Alice pays 0 + 0 + 0 + 4 = 4. So Bob&#39;s relative loss is 38 - 4 = 34.
+For the 2<sup>nd</sup> query Bob selects the chocolates with prices [19,22]. He pays 5 + 5 = 10 and Alice pays 14 + 17 = 31. So Bob&#39;s relative loss is 10 - 31 = -21.
+It can be shown that these are the minimum possible relative losses.</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [1,5,4,3,7,11,9], queries = [[5,4],[5,7],[7,3],[4,5]]
+<strong>Output:</strong> [4,16,7,1]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolates with prices [1,3,9,11]. He pays 1 + 3 + 5 + 5 = 14 and Alice pays 0 + 0 + 4 + 6 = 10. So Bob&#39;s relative loss is 14 - 10 = 4.
+For the 2<sup>nd</sup> query Bob has to select all the chocolates. He pays 1 + 5 + 4 + 3 + 5 + 5 + 5 = 28 and Alice pays 0 + 0 + 0 + 0 + 2 + 6 + 4 = 12. So Bob&#39;s relative loss is 28 - 12 = 16.
+For the 3<sup>rd</sup> query Bob selects the chocolates with prices [1,3,11] and he pays 1 + 3 + 7 = 11 and Alice pays 0 + 0 + 4 = 4. So Bob&#39;s relative loss is 11 - 4 = 7.
+For the 4<sup>th</sup> query Bob selects the chocolates with prices [1,3,7,9,11] and he pays 1 + 3 + 4 + 4 + 4 = 16 and Alice pays 0 + 0 + 3 + 5 + 7 = 15. So Bob&#39;s relative loss is 16 - 15 = 1.
+It can be shown that these are the minimum possible relative losses.
+</pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [5,6,7], queries = [[10,1],[5,3],[3,3]]
+<strong>Output:</strong> [5,12,0]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolate with price 5 and he pays 5 and Alice pays 0. So Bob&#39;s relative loss is 5 - 0 = 5.
+For the 2<sup>nd</sup> query Bob has to select all the chocolates. He pays 5 + 5 + 5 = 15 and Alice pays 0 + 1 + 2 = 3. So Bob&#39;s relative loss is 15 - 3 = 12.
+For the 3<sup>rd</sup> query Bob has to select all the chocolates. He pays 3 + 3 + 3 = 9 and Alice pays 2 + 3 + 4 = 9. So Bob&#39;s relative loss is 9 - 9 = 0.
+It can be shown that these are the minimum possible relative losses.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= prices.length == n &lt;= 10<sup>5</sup></code></li>
+	<li><code>1 &lt;= prices[i] &lt;= 10<sup>9</sup></code></li>
+	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>queries[i].length == 2</code></li>
+	<li><code>1 &lt;= k<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
+	<li><code>1 &lt;= m<sub>i</sub> &lt;= n</code></li>
+</ul>
+
+## 解法
+
+<!-- 这里可写通用的实现逻辑 -->
+
+<!-- tabs:start -->
+
+### **Python3**
+
+<!-- 这里可写当前语言的特殊实现逻辑 -->
+
+```python
+
+```
+
+### **Java**
+
+<!-- 这里可写当前语言的特殊实现逻辑 -->
+
+```java
+
+```
+
+### **C++**
+
+```cpp
+
+```
+
+### **Go**
+
+```go
+
+```
+
+### **...**
+
+```
+
+```
+
+<!-- tabs:end -->

solution/2800-2899/2819.Minimum Relative Loss After Buying Chocolates/README_EN.md

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+# [2819. Minimum Relative Loss After Buying Chocolates](https://leetcode.com/problems/minimum-relative-loss-after-buying-chocolates)
+
+[中文文档](/solution/2800-2899/2819.Minimum%20Relative%20Loss%20After%20Buying%20Chocolates/README.md)
+
+## Description
+
+<p>You are given an integer array <code>prices</code>, which shows the chocolate prices and a 2D integer array <code>queries</code>, where <code>queries[i] = [k<sub>i</sub>, m<sub>i</sub>]</code>.</p>
+
+<p>Alice and Bob went to buy some chocolates, and Alice suggested a way to pay for them, and Bob agreed.</p>
+
+<p>The terms for each query are as follows:</p>
+
+<ul>
+	<li>If the price of a chocolate is <strong>less than or equal to</strong> <code>k<sub>i</sub></code>, Bob pays for it.</li>
+	<li>Otherwise, Bob pays <code>k<sub>i</sub></code> of it, and Alice pays the <strong>rest</strong>.</li>
+</ul>
+
+<p>Bob wants to select <strong>exactly</strong> <code>m<sub>i</sub></code> chocolates such that his <strong>relative loss</strong> is <strong>minimized</strong>, more formally, if, in total, Alice has paid <code>a<sub>i</sub></code> and Bob has paid <code>b<sub>i</sub></code>, Bob wants to minimize <code>b<sub>i</sub> - a<sub>i</sub></code>.</p>
+
+<p>Return <em>an integer array</em> <code>ans</code> <em>where</em> <code>ans[i]</code> <em>is Bob&#39;s <strong>minimum relative loss </strong>possible for</em> <code>queries[i]</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [1,9,22,10,19], queries = [[18,4],[5,2]]
+<strong>Output:</strong> [34,-21]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolates with prices [1,9,10,22]. He pays 1 + 9 + 10 + 18 = 38 and Alice pays 0 + 0 + 0 + 4 = 4. So Bob&#39;s relative loss is 38 - 4 = 34.
+For the 2<sup>nd</sup> query Bob selects the chocolates with prices [19,22]. He pays 5 + 5 = 10 and Alice pays 14 + 17 = 31. So Bob&#39;s relative loss is 10 - 31 = -21.
+It can be shown that these are the minimum possible relative losses.</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [1,5,4,3,7,11,9], queries = [[5,4],[5,7],[7,3],[4,5]]
+<strong>Output:</strong> [4,16,7,1]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolates with prices [1,3,9,11]. He pays 1 + 3 + 5 + 5 = 14 and Alice pays 0 + 0 + 4 + 6 = 10. So Bob&#39;s relative loss is 14 - 10 = 4.
+For the 2<sup>nd</sup> query Bob has to select all the chocolates. He pays 1 + 5 + 4 + 3 + 5 + 5 + 5 = 28 and Alice pays 0 + 0 + 0 + 0 + 2 + 6 + 4 = 12. So Bob&#39;s relative loss is 28 - 12 = 16.
+For the 3<sup>rd</sup> query Bob selects the chocolates with prices [1,3,11] and he pays 1 + 3 + 7 = 11 and Alice pays 0 + 0 + 4 = 4. So Bob&#39;s relative loss is 11 - 4 = 7.
+For the 4<sup>th</sup> query Bob selects the chocolates with prices [1,3,7,9,11] and he pays 1 + 3 + 4 + 4 + 4 = 16 and Alice pays 0 + 0 + 3 + 5 + 7 = 15. So Bob&#39;s relative loss is 16 - 15 = 1.
+It can be shown that these are the minimum possible relative losses.
+</pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> prices = [5,6,7], queries = [[10,1],[5,3],[3,3]]
+<strong>Output:</strong> [5,12,0]
+<strong>Explanation:</strong> For the 1<sup>st</sup> query Bob selects the chocolate with price 5 and he pays 5 and Alice pays 0. So Bob&#39;s relative loss is 5 - 0 = 5.
+For the 2<sup>nd</sup> query Bob has to select all the chocolates. He pays 5 + 5 + 5 = 15 and Alice pays 0 + 1 + 2 = 3. So Bob&#39;s relative loss is 15 - 3 = 12.
+For the 3<sup>rd</sup> query Bob has to select all the chocolates. He pays 3 + 3 + 3 = 9 and Alice pays 2 + 3 + 4 = 9. So Bob&#39;s relative loss is 9 - 9 = 0.
+It can be shown that these are the minimum possible relative losses.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= prices.length == n &lt;= 10<sup>5</sup></code></li>
+	<li><code>1 &lt;= prices[i] &lt;= 10<sup>9</sup></code></li>
+	<li><code>1 &lt;= queries.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>queries[i].length == 2</code></li>
+	<li><code>1 &lt;= k<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
+	<li><code>1 &lt;= m<sub>i</sub> &lt;= n</code></li>
+</ul>
+
+## Solutions
+
+<!-- tabs:start -->
+
+### **Python3**
+
+```python
+
+```
+
+### **Java**
+
+```java
+
+```
+
+### **C++**
+
+```cpp
+
+```
+
+### **Go**
+
+```go
+
+```
+
+### **...**
+
+```
+
+```
+
+<!-- tabs:end -->

solution/2800-2899/2820.Election Results/README.md

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+# [2820. Election Results](https://leetcode.cn/problems/election-results)
+
+[English Version](/solution/2800-2899/2820.Election%20Results/README_EN.md)
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>Table: <code><font face="monospace">Votes</font></code></p>
+
+<pre>
++-------------+---------+ 
+| Column Name | Type    | 
++-------------+---------+ 
+| voter       | varchar | 
+| candidate   | varchar |
++-------------+---------+
+(voter, candidate) is the primary key for this table.
+Each row of this table contains name of the voter and their candidate. 
+</pre>
+
+<p>The election is conducted in a city where everyone can vote for <strong>one or more</strong> candidates or choose <strong>not</strong> to vote. Each person has <code>1</code><strong> vote</strong> so if they vote for multiple candidates, their vote gets equally split across them. For example, if a person votes for <code>2</code> candidates, these candidates receive an equivalent of <code>0.5</code>&nbsp;votes each.</p>
+
+<p>Write an SQL query to find <code>candidate</code> who got the most votes and won the election. Output the name of the <strong>candidate</strong> or If multiple candidates have an <strong>equal number</strong> of votes, display the names of all of them.</p>
+
+<p>Return<em> the result table ordered</em> <em>by</em> <code>candidate</code> <em>in <strong>ascending</strong> order.</em></p>
+
+<p>The query result format is in the following example.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> 
+Votes table:
++----------+-----------+
+| voter    | candidate |
++----------+-----------+
+| Kathy    | null      |
+| Charles  | Ryan      |
+| Charles  | Christine |
+| Charles  | Kathy     |
+| Benjamin | Christine |
+| Anthony  | Ryan      |
+| Edward   | Ryan      |
+| Terry    | null      |
+| Evelyn   | Kathy     |
+| Arthur   | Christine |
++----------+-----------+
+<strong>Output:</strong> 
++-----------+
+| candidate | 
++-----------+
+| Christine |  
+| Ryan      |  
++-----------+
+<strong>Explanation:</strong> 
+- Kathy and Terry opted not to participate in voting, resulting in their votes being recorded as 0. Charles distributed his vote among three candidates, equating to 0.33 for each candidate. On the other hand, Benjamin, Arthur, Anthony, Edward, and Evelyn each cast their votes for a single candidate.
+- Collectively, Candidate Ryan and Christine amassed a total of 2.33 votes, while Kathy received a combined total of 1.33 votes.
+Since Ryan and Christine received an equal number of votes, we will display their names in ascending order.</pre>
+
+## 解法
+
+<!-- 这里可写通用的实现逻辑 -->
+
+**方法一：窗口函数 + 分组统计**
+
+我们可以使用窗口函数 `count` 计算每个投票人投给的候选人的票数，然后再使用分组统计函数 `sum` 计算每个候选人的总票数，最后使用窗口函数 `rank` 计算每个候选人的排名，最后筛选出排名第一的候选人即可。
+
+注意，结果集中可能会有多个排名第一的候选人，因此我们需要使用 `order by` 对候选人进行排序。
+
+<!-- tabs:start -->
+
+### **SQL**
+
+<!-- 这里可写当前语言的特殊实现逻辑 -->
+
+```sql
+# Write your MySQL query statement below
+WITH
+    T AS (
+        SELECT candidate, sum(vote) AS tot
+        FROM
+            (
+                SELECT
+                    candidate,
+                    1 / (count(candidate) OVER (PARTITION BY voter)) AS vote
+                FROM Votes
+                WHERE candidate IS NOT NULL
+            ) AS t
+        GROUP BY 1
+    ),
+    P AS (
+        SELECT
+            candidate,
+            rank() OVER (ORDER BY tot DESC) AS rk
+        FROM T
+    )
+SELECT candidate
+FROM P
+WHERE rk = 1
+ORDER BY 1;
+```
+
+<!-- tabs:end -->