Data Science & LeetCode for Kindergarten

Leetcode SQL 175. Combine Two Tables

題目:

Table: Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| PersonId    | int     |
| FirstName   | varchar |
| LastName    | varchar |
+-------------+---------+
PersonId is…

607. Sales Person

Table: SalesPerson

+-----------------+---------+
| Column Name     | Type    |
+-----------------+---------+
| sales_id        | int     |
| name            | varchar |
| salary          | int     |
| commission_rate | int     |
| hire_date       | date    |…

8. String to Integer (atoi)

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function).

The algorithm for myAtoi(string s) is as follows:

1. Read in and ignore any leading whitespace.

371. Sum of Two Integers

Given two integers a and b, return the sum of the two integers without using the operators + and -.

Example 1:

Input: a = 1, b = 2
Output: 3

Example 2:

Input: a = 2, b = 3
Output: 5

LeetCode 21. Merge Two Sorted Lists

題目:

Input: l1 = [1,2,4], l2 = [1,3,4]
Output: [1,1,2,3,4,4]

連接兩個List，數字由小至大。

思路:

1. l1,l2資料結構是ListNode

Leetcode MySQL 183. Customers Who Never Order

題目:

給兩個表，一個顧客名子，一個有買東西的顧客的名單，接著求列出沒買東西的人的名單。

Table: Customers.

+----+-------+
| Id | Name  |
+----+-------+
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |…

1873. Calculate Special Bonus

Table: Employees

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| employee_id | int     |
| name        | varchar |
| salary      | int     |
+-------------+---------+
employee_id is the primary key for this table.
Each…

Leetcode MySQL 185. Department Top Three Salaries

題目:

列出各Department 中Salary 前三高的名單。

The Employee table holds all employees. Every employee has an Id, and there is also a column for the department Id.