基本原则:
先进先出，后进后出。 FIFO

普通队列

#include <iostream>
#include <cassert>
using namespace std;
class Queue {
private:
    int *data;
    int head, tail, length;
public:
    Queue(int length_input) {
        data = new int[length_input];
        length = length_input;
        head = 0;
        tail = -1;
    }

队列的构成：保存数据的数组 data【】
** 队列长度，也就是数组长度加一，length**
** 记录队首元素位置的head（index）**
** 记录队尾元素位置的tail（index）**

~Queue() {
delete[] data;
}

---
##入队

---

void push(int element) {
    if (tail + 1 < length) {
        tail++;
        data[tail] = element;
    }
}

>**思路：直接将tail++，然后将入队的值赋予data[tail]**

---
** **
    void output() {
        for (int i = head; i <= tail; i++) {
            cout << data[i] << " ";
        }
        cout << endl;
    }

** **
    int front(){
    assert(head<=tail);
     return data[head];     
    }

##出队
** **
    void pop(){
    assert(head<=tail);
        head++;
    }
**思路：直接将记录队首元素的head++；**

** **
};

int main() {
Queue queue(100);
for (int i = 1; i <= 10; i++) {
queue.push(i);
}
queue.output();
cout<< queue.front()<<endl;
queue.pop();
queue.output();
return 0;
}

------------------------------------------------------------------------------------------------
##循环队列

include <iostream>

include <cassert>

using namespace std;
class Queue {
private:
int *data;
int head, tail, length, count;
public:
Queue(int length_input) {
data = new int[length_input];
length = length_input;
head = 0;
tail = -1;
count = 0;
}

**队列的构成：保存数据的数组 data【】**
**                    队列长度，也就是数组长度加一，length**
**                    记录队首元素位置的head（index）**
**                    记录队尾元素位置的tail（index）**
**                    记录队列元素数量的count**

** **
    ~Queue() {
        delete[] data;
    }
    bool push(int element) {
        if (count < length) {
            tail = (tail + 1) % length;
            data[tail] = element;
            count++;
            return true;
        } else {
            return false;
        }
    }
    void output() {
        for (int i = head; i != tail + 1; i = (i + 1) % length) {
            cout << data[i] << " ";
        }
        cout << endl;
    }
    int front() {
        assert(count>0);
        return data[head];
    }
    void pop() {
        assert(count>0);
        head=(head+1)%length;
        count--;
    }
};

int main() {
Queue queue(100);
for (int i = 1; i <= 10; i++) {
queue.push(i);
}
queue.output();
cout << queue.front() << endl;
queue.pop();
queue.output();
return 0;
}