STL学习笔记——1.queue

STL学习笔记——1.queue
 之前被学长坑了，非要模拟队列，以至于现在完全看不懂网上用STL写的代码，只有现学了(╯‵□′)╯︵┻━┻。
以下资料主要参考网站http://www.cplusplus.com/reference/queue/
classtemplate 
<queue>
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std::queue
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template <class T, class Container =deque<T> > class queue;
FIFOqueue
queues area type of container adaptor, specifically designed to operate in a FIFO context(first-in first-out), where elements are inserted into one end of the containerand extracted from the other. queues are implemented as containers adaptors, which are classesthat use an encapsulated object of a specific container class as its underlyingcontainer, providing a specific set of member functions to access itselements. Elements are pushed into the "back" of thespecific container and popped from its "front". The underlying container may be one of the standard container class template orsome other specifically designed container class. This underlying containershall support at least the following operations:
<ul type="disc"><li style="background:white; color:black">empty </li><li style="background:white; color:black">size </li><li style="background:white; color:black">front </li><li style="background:white; color:black">back </li><li style="background:white; color:black">push_back </li><li style="background:white; color:black">pop_front</li></ul>
队列的特点如上文，简单而言就是FIFO，即First In First Out，也就是先入先出。主要形式要注意：
●头文件 #include<queue>(或者直接写#include<bits/stdc++.h>)
●声明：
如果之前已经声明了命名空间：using namespace std;
则直接写：queue<变量类型（如int||char）> 变量名称（选一个自己喜欢的就好罒ω罒）
如果之前没有声明命名空间，则写：
std::queue<变量类型（如int||char）> 变量名称（选一个自己喜欢的就好罒ω罒）
●常用函数：
 empty:
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std::<a href="http://www.cplusplus.com/reference/queue/queue/" rel="noopener noreferrer" target="_blank">queue</a>::empty
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bool empty() const;
Test whethercontainer is empty
Ret