7.Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

整数反转，忽略符号部分。

1. Two Sum

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9

Output: index1=1, index2=2

给定一个整型数组，找到两个数，使得两个数相加的和为指定的目标数；

1.database 数据库

A database is an organized collection of data. The data is typically organized to model aspects of reality in a way that supports processes requiring information.

数据库，简单来说可视为电子化的文件柜——存储电子文件的处所，用户可以对文件中的数据运行新增、截取、更新、删除等操作。

数据库指的是以一定方式储存在一起、能为多个用户共享、具有尽可能小的冗余度、与应用程序彼此独立的数据集合。