算法导论-------------队列（queue）的简单实现

               队列的基本操作包括入队enqueue和出队dequeue，队列有队头head和队尾tail指针。元素总是从队头出，从队尾入。采用数组实现队列时候，为了合理利用空间，可以采用循环实现队列空间的有效利用。     

                                               

                                                                  

#include<iostream>using namespace std;struct queue{int *q;int queuesize;int head;int tail;};void init(queue* q, int n){q->head = 0;q->tail = 0;q->queuesize = n;q->q = (int*)malloc(sizeof(int)*q->queuesize);}void enqueue(queue* q, int x){if (((q->tail + 1) % q->queuesize) == q->head){cout << "queue is full" << endl;}else{q->q[q->tail] = x;q->tail = (q->tail + 1) % q->queuesize;}}int dequeue(queue* q, int *value){if (q->tail == q->head)return -1;else{*value = q->q[q->head];q->head = ((q->head++) % q->queuesize);}}int main(){int value;queue q;init(&q, 10);for (int i = 0; i < 9; i++){enqueue(&q, i + 11);}cout << "head=" << q.head << endl;cout << "tail=" << q.tail << endl;for (int i = 0; i < 9; i++){if (dequeue(&q, &value) == -1)cout << "queque is empy"<<endl;elseprintf("value=%d\n", value);}cout << "head=" << q.head << endl;cout << "tail=" << q.tail << endl;return 0;}