c++ 双端队列 deque 之 (头部、尾部)插入元素/删除元素/
//insert elements in first a.push_front(some_element)//insert elements at last a.push_back(some_element);//pop element at first a.pop_front(some_element);//pop element at last a.pop_back(some_element);#include <iostream>#inclu
