Leetcode SQL 175. Combine Two Tables

題目:

Table: Person

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

Leetcode MySQL 176. Second Highest Salary

題目:

Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

LeetCode 9. Palindrome Number

題目:

Input: x = 121
Output: true

Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

LeetCode 13. Roman to Integer

題目:

Symbol       Value
I             1
V             5
X             10
L             50
C             100
D             500
M             1000

Input: s = "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV…