feat: add new lc problems and solutions: No.2784~2791 (doocs#1276)

* No.2784. Check if Array is Good
* No.2785. Sort Vowels in a String
* No.2786. Visit Array Positions to Maximize Score
* No.2787. Ways to Express an Integer as Sum of Powers
* No.2788. Split Strings by Separator
* No.2789. Largest Element in an Array after Merge Operations
* No.2790. Maximum Number of Groups With Increasing Length
* No.2791. Count Paths That Can Form a Palindrome in a Tree

Author: yanglbme

solution/0100-0199/0176.Second Highest Salary/README.md

@@ -17,13 +17,13 @@
 | id          | int  |
 | salary      | int  |
 +-------------+------+
-id 是这个表的主键。
+在 SQL 中，id 是这个表的主键。
 表的每一行包含员工的工资信息。
 </pre>
 
 <p>&nbsp;</p>
 
-<p>编写一个 SQL 查询，获取并返回 <code>Employee</code>&nbsp;表中第二高的薪水 。如果不存在第二高的薪水，查询应该返回 <code>null</code> 。</p>
+<p>查询并返回 <code>Employee</code>&nbsp;表中第二高的薪水 。如果不存在第二高的薪水，查询应该返回 <code>null(Pandas 则返回 None)</code> 。</p>
 
 <p>查询结果如下例所示。</p>
 

solution/0100-0199/0176.Second Highest Salary/README_EN.md

@@ -13,13 +13,13 @@
 | id          | int  |
 | salary      | int  |
 +-------------+------+
-id is the primary key column for this table.
+In SQL, id is the primary key column for this table.
 Each row of this table contains information about the salary of an employee.
 </pre>
 
 <p>&nbsp;</p>
 
-<p>Find&nbsp;the second highest salary from the <code>Employee</code> table. If there is no second highest salary,&nbsp;return&nbsp;<code>null</code>.</p>
+<p>Find&nbsp;the second highest salary from the <code>Employee</code> table. If there is no second highest salary,&nbsp;return&nbsp;<code>null (return&nbsp;None in Pandas)</code>.</p>
 
 <p>The result format is in the following example.</p>
 

solution/0100-0199/0177.Nth Highest Salary/README.md

@@ -15,13 +15,13 @@
 | id          | int  |
 | salary      | int  |
 +-------------+------+
-Id是该表的主键列。
+在 SQL 中，id 是该表的主键。
 该表的每一行都包含有关员工工资的信息。
 </pre>
 
 <p>&nbsp;</p>
 
-<p>编写一个SQL查询来报告 <code>Employee</code> 表中第 <code>n</code> 高的工资。如果没有第 <code>n</code> 个最高工资，查询应该报告为&nbsp;<code>null</code> 。</p>
+<p>查询&nbsp;<code>Employee</code> 表中第 <code>n</code> 高的工资。如果没有第 <code>n</code> 个最高工资，查询结果应该为&nbsp;<code>null</code> 。</p>
 
 <p>查询结果格式如下所示。</p>
 

solution/0100-0199/0177.Nth Highest Salary/README_EN.md

@@ -13,7 +13,7 @@
 | id          | int  |
 | salary      | int  |
 +-------------+------+
-id is the primary key column for this table.
+In SQL, id is the primary key column for this table.
 Each row of this table contains information about the salary of an employee.
 </pre>
 

solution/0100-0199/0178.Rank Scores/README.md

@@ -15,13 +15,13 @@
 | id          | int     |
 | score       | decimal |
 +-------------+---------+
-Id是该表的主键。
-该表的每一行都包含了一场比赛的分数。Score是一个有两位小数点的浮点值。
+在 SQL 中，id 是该表的主键。
+该表的每一行都包含了一场比赛的分数。Score 是一个有两位小数点的浮点值。
 </pre>
 
 <p>&nbsp;</p>
 
-<p>编写 SQL 查询对分数进行排序。排名按以下规则计算:</p>
+<p>查询并对分数进行排序。排名按以下规则计算:</p>
 
 <ul>
 	<li>分数应按从高到低排列。</li>

solution/0100-0199/0178.Rank Scores/README_EN.md

@@ -13,7 +13,7 @@
 | id          | int     |
 | score       | decimal |
 +-------------+---------+
-id is the primary key for this table.
+In SQL, id is the primary key for this table.
 Each row of this table contains the score of a game. Score is a floating point value with two decimal places.
 </pre>
 

solution/0100-0199/0183.Customers Who Never Order/README.md

@@ -6,39 +6,68 @@
 
 <!-- 这里写题目描述 -->
 
-<p>某网站包含两个表，<code>Customers</code> 表和 <code>Orders</code> 表。编写一个 SQL 查询，找出所有从不订购任何东西的客户。</p>
-
 <p><code>Customers</code> 表：</p>
 
-<pre>+----+-------+
-| Id | Name  |
+<pre>
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| id          | int     |
+| name        | varchar |
++-------------+---------+
+在 SQL 中，id 是该表的主键。
+该表的每一行都表示客户的 ID 和名称。</pre>
+
+<p><code>Orders</code> 表：</p>
+
+<pre>
++-------------+------+
+| Column Name | Type |
++-------------+------+
+| id          | int  |
+| customerId  | int  |
++-------------+------+
+在 SQL 中，id 是该表的主键。
+customerId 是 Customers 表中 ID 的外键( Pandas 中的连接键)。
+该表的每一行都表示订单的 ID 和订购该订单的客户的 ID。</pre>
+
+<p>&nbsp;</p>
+
+<p>找出所有从不点任何东西的顾客。</p>
+
+<p>以 <strong>任意顺序</strong> 返回结果表。</p>
+
+<p>结果格式如下所示。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<b>输入：</b>
+Customers table:
++----+-------+
+| id | name  |
 +----+-------+
 | 1  | Joe   |
 | 2  | Henry |
 | 3  | Sam   |
 | 4  | Max   |
 +----+-------+
-</pre>
-
-<p><code>Orders</code> 表：</p>
-
-<pre>+----+------------+
-| Id | CustomerId |
+Orders table:
++----+------------+
+| id | customerId |
 +----+------------+
 | 1  | 3          |
 | 2  | 1          |
 +----+------------+
-</pre>
-
-<p>例如给定上述表格，你的查询应返回：</p>
-
-<pre>+-----------+
+<b>输出：</b>
++-----------+
 | Customers |
 +-----------+
 | Henry     |
 | Max       |
-+-----------+
-</pre>
++-----------+</pre>
 
 ## 解法
 

solution/0100-0199/0183.Customers Who Never Order/README_EN.md

@@ -13,7 +13,7 @@
 | id          | int     |
 | name        | varchar |
 +-------------+---------+
-id is the primary key column for this table.
+In SQL, id is the primary key column for this table.
 Each row of this table indicates the ID and name of a customer.
 </pre>
 
@@ -28,8 +28,8 @@ Each row of this table indicates the ID and name of a customer.
 | id          | int  |
 | customerId  | int  |
 +-------------+------+
-id is the primary key column for this table.
-customerId is a foreign key of the ID from the Customers table.
+In SQL, id is the primary key column for this table.
+customerId is a foreign key (join key in Pandas) of the ID from the Customers table.
 Each row of this table indicates the ID of an order and the ID of the customer who ordered it.
 </pre>
 

solution/0100-0199/0184.Department Highest Salary/README.md

@@ -17,9 +17,9 @@
 | salary       | int     |
 | departmentId | int     |
 +--------------+---------+
-id是此表的主键列。
-departmentId是Department表中ID的外键。
-此表的每一行都表示员工的ID、姓名和工资。它还包含他们所在部门的ID。
+在 SQL 中，id是此表的主键。
+departmentId 是 Department 表中 id 的外键（在 Pandas 中称为 join key）。
+此表的每一行都表示员工的 id、姓名和工资。它还包含他们所在部门的 id。
 </pre>
 
 <p>&nbsp;</p>
@@ -33,13 +33,13 @@ departmentId是Department表中ID的外键。
 | id          | int     |
 | name        | varchar |
 +-------------+---------+
-id是此表的主键列。
-此表的每一行都表示一个部门的ID及其名称。
+在 SQL 中，id 是此表的主键列。
+此表的每一行都表示一个部门的 id 及其名称。
 </pre>
 
 <p>&nbsp;</p>
 
-<p>编写SQL查询以查找每个部门中薪资最高的员工。<br />
+<p>查找出每个部门中薪资最高的员工。<br />
 按 <strong>任意顺序</strong> 返回结果表。<br />
 查询结果格式如下例所示。</p>
 

solution/0100-0199/0184.Department Highest Salary/README_EN.md

@@ -15,8 +15,8 @@
 | salary       | int     |
 | departmentId | int     |
 +--------------+---------+
-id is the primary key column for this table.
-departmentId is a foreign key of the ID from the <code>Department </code>table.
+In SQL, id is the primary key column for this table.
+departmentId is a foreign key (join key in Pandas) of the ID from the <code>Department </code>table.
 Each row of this table indicates the ID, name, and salary of an employee. It also contains the ID of their department.
 </pre>
 
@@ -31,7 +31,7 @@ Each row of this table indicates the ID, name, and salary of an employee. It als
 | id          | int     |
 | name        | varchar |
 +-------------+---------+
-id is the primary key column for this table. It is guaranteed that department name is not <code>NULL.</code>
+In SQL, id is the primary key column for this table. It is guaranteed that department name is not <code>NULL.</code>
 Each row of this table indicates the ID of a department and its name.
 </pre>