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#include<iostream>
using namespace std;
template<typename T>
struct node {
T value;
node<T>* next;
};
template<class T>
class queue {
public:
queue() : _head{nullptr} {}
~queue() {
auto iter = _head;
while(iter) {
delete iter;
iter = iter->next;
}
}
queue<T>* enqueue(T val) {
if(!_head) {
_head = new node<T>{val, nullptr};
_tail = _head;
} else {
_tail->next = new node<T>{val, nullptr};
_tail = _tail->next;
}
return this;
}
node<T>* dequeue() {
if(!_head) return nullptr;
auto iter = _head;
delete _head;
_head = iter->next;
return iter;
}
void print() {
auto iter = _head;
while(iter) {
cout << iter->value << ' ';
iter = iter->next;
}
cout << endl;
}
private:
node<T>* _head;
node<T>* _tail;
};
int main() {
queue<int>* q = new queue<int>();
q->dequeue();
q->enqueue(4)->enqueue(2)->enqueue(8);
q->print();
auto e = q->dequeue();
if(e)
cout << e->value << endl;
q->enqueue(1);
q->print();
delete q;
return 0;
}
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