feat(leetcode): new easy/medium solutions

Author: jestenough

services/leetcode/problems/175-combine-two-tables/README.md

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+# 175. Combine Two Tables
+
+Table: Person
+
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| personId    | int     |
+| lastName    | varchar |
+| firstName   | varchar |
++-------------+---------+
+personId is the primary key (column with unique values) for this table.
+This table contains information about the ID of some persons and their first and last names.
+
+ 
+
+Table: Address
+
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| addressId   | int     |
+| personId    | int     |
+| city        | varchar |
+| state       | varchar |
++-------------+---------+
+addressId is the primary key (column with unique values) for this table.
+Each row of this table contains information about the city and state of one person with ID = PersonId.
+
+ 
+
+Write a solution to report the first name, last name, city, and state of each person in the Person table. If the address of a personId is not present in the Address table, report null instead.
+
+Return the result table in any order.
+
+The result format is in the following example.
+
+[Link to problem](https://leetcode.com/problems/combine-two-tables/)

services/leetcode/problems/175-combine-two-tables/solution.sql

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+SELECT p.firstName, p.lastName, a.city, a.state
+FROM Person as p
+LEFT JOIN Address as a ON a.personId = p.personId

services/leetcode/problems/176-second-highest-salary/README.md

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+# 176. Second Highest Salary
+
+Table: Employee
+
++-------------+------+
+| Column Name | Type |
++-------------+------+
+| id          | int  |
+| salary      | int  |
++-------------+------+
+id is the primary key (column with unique values) for this table.
+Each row of this table contains information about the salary of an employee.
+
+ 
+
+Write a solution to find the second highest distinct salary from the Employee table. If there is no second highest salary, return null (return None in Pandas).
+
+The result format is in the following example.
+
+[Link to problem](https://leetcode.com/problems/second-highest-salary/)

services/leetcode/problems/176-second-highest-salary/solution.sql

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+SELECT (
+    SELECT DISTINCT salary
+    FROM Employee
+    ORDER BY salary DESC
+    OFFSET 1 LIMIT 1
+) AS "SecondHighestSalary";

services/leetcode/problems/177-nth-highest-salary/README.md

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+# 177. Nth Highest Salary
+
+Table: Employee
+
++-------------+------+
+| Column Name | Type |
++-------------+------+
+| id          | int  |
+| salary      | int  |
++-------------+------+
+id is the primary key (column with unique values) for this table.
+Each row of this table contains information about the salary of an employee.
+
+ 
+
+Write a solution to find the nth highest distinct salary from the Employee table. If there are less than n distinct salaries, return null.
+
+The result format is in the following example.
+
+[Link to problem](https://leetcode.com/problems/nth-highest-salary/)

services/leetcode/problems/177-nth-highest-salary/solution.sql

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+CREATE OR REPLACE FUNCTION NthHighestSalary(N INT) RETURNS TABLE (Salary INT) AS $$
+BEGIN
+  IF n <= 0 THEN
+    RETURN;
+  END IF;
+
+  RETURN QUERY
+    SELECT DISTINCT e.salary
+    FROM employee e
+    ORDER BY salary DESC
+    OFFSET n-1 LIMIT 1;
+END;
+$$ LANGUAGE plpgsql;

services/leetcode/problems/178-rank-scores/README.md

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+# 178. Rank Scores
+
+Table: Scores
+
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| id          | int     |
+| score       | decimal |
++-------------+---------+
+id is the primary key (column with unique values) for this table.
+Each row of this table contains the score of a game. Score is a floating point value with two decimal places.
+
+ 
+
+Write a solution to find the rank of the scores. The ranking should be calculated according to the following rules:
+
+    The scores should be ranked from the highest to the lowest.
+    If there is a tie between two scores, both should have the same ranking.
+    After a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no holes between ranks.
+
+Return the result table ordered by score in descending order.
+
+The result format is in the following example.
+
+[Link to problem](https://leetcode.com/problems/rank-scores/)

services/leetcode/problems/178-rank-scores/solution.sql

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+SELECT score, DENSE_RANK() OVER (ORDER BY score DESC) rank
+FROM Scores

services/leetcode/problems/1935-maximum-number-of-words-you-can-type/README.md

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+# 1935. Maximum Number of Words You Can Type
+
+There is a malfunctioning keyboard where some letter keys do not work. All other keys on the keyboard work properly.
+
+Given a string text of words separated by a single space (no leading or trailing spaces) and a string brokenLetters of all distinct letter keys that are broken, return the number of words in text you can fully type using this keyboard.
+
+[Link to problem](https://leetcode.com/problems/maximum-number-of-words-you-can-types)

services/leetcode/problems/1935-maximum-number-of-words-you-can-type/solution.py

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+class Solution:
+    def canBeTypedWords(self, text: str, brokenLetters: str) -> int:
+        count = 0
+        for word in text.split(" "):
+            for broken_letter in brokenLetters:
+                if word.find(broken_letter) != -1:
+                    break
+            else:
+                count += 1
+
+        return count