对称密码体制
对称密码体制要求加密与解密使用同一个共享密钥，解密是加密的逆运算，由于通信双方共享同一个密钥，这就要求通信双方必须在通信前商定该密钥，并妥善保存该密钥。该密钥称为秘密密钥。秘密密钥的存在使得对称密码体制开放性变差。
对称密码体制分为两种：一种是对明文的单个位（或字节）进行加密和解密，称为流密码，又
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【RabbitMQ实战】虚拟主机
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每一个RabbitMQ服务器都能创建虚拟消息服务器，称之为虚拟主机（vhost）。
【RabbitMQ实战】AMQP元素——交换器、队列和绑定
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Message Queue
AMQP消息路由必须有三部分：交换器、队列和绑定。生产者把消息发布到交换器上；消息最终到达队列，并被消费者接收；绑定决定了消息如何从路由器路由到特定的队列。
从底部开始构造：队列消费者通过以下两种方式从特定的队列中接受消息：（1）通过AMQP的basic.consume命令订阅。这样做会将信道置为
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【RabbitMQ实战】消息通信概念——消费者、生产者和代理
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Message Queue
生产者（producer）创建消息，然后发布（发送）到代理服务器（RabbitMQ）。
消息包含两部分内容：有效载荷（payload）和标签（label）。有效载荷就是想要传输的数据。它可以是任何内容。标签描述了有效载荷，并且RabbitMQ用它来决定谁将获得消息的拷贝。举例来说，不同于TCP协议的
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[LeetCode] Problem 994 - Rotting Oranges
In a given grid, each cell can have one of three values:
the value 0 representing an empty cell;
the value 1 representing a fresh orange;
the value 2
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[LeetCode] Problem 860 - Lemonade Change
At a lemonade stand, each lemonade costs $5.
Customers are standing in a queue to buy from you, and order one at a time (in the order specified by bi
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[LeetCode] Problem 824 - Goat Latin
A sentence S is given, composed of words separated by spaces. Each word consists of lowercase and uppercase letters only.
We would like to convert the
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[LeetCode] Problem 892 - Surface Area of 3D Shapes
On a N * N grid, we place some 1 * 1 * 1 cubes.
Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j).
Return the
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[LeetCode] Problem 976 - Largest Perimeter Triangle
Given an array A of positive lengths, return the largest perimeter of a triangle with non-zero area, formed from 3 of these lengths.
If it is impossib
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[LeetCode] Problem 812 - Largest Triangle Area
You have a list of points in the plane. Return the area of the largest triangle that can be formed by any 3 of the points.
ExampleInput: points = [[0,
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