138 lines
3.4 KiB
C++
138 lines
3.4 KiB
C++
/*
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* File: array_queue.cpp
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* Created Time: 2022-11-25
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* Author: Krahets (krahets@163.com)
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*/
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#include "../include/include.hpp"
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/* 基于环形数组实现的队列 */
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class ArrayQueue {
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private:
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int *nums; // 用于存储队列元素的数组
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int cap; // 队列容量
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int front = 0; // 头指针，指向队首
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int rear = 0; // 尾指针，指向队尾 + 1
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public:
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ArrayQueue(int capacity) {
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// 初始化数组
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cap = capacity;
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nums = new int[capacity];
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}
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/* 获取队列的容量 */
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int capacity() {
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return cap;
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}
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/* 获取队列的长度 */
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int size() {
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// 由于将数组看作为环形，可能 rear < front ，因此需要取余数
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return (capacity() + rear - front) % capacity();
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}
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/* 判断队列是否为空 */
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bool empty() {
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return rear - front == 0;
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}
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/* 入队 */
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void offer(int num) {
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if (size() == capacity()) {
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cout << "队列已满" << endl;
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return;
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}
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// 尾结点后添加 num
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nums[rear] = num;
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// 尾指针向后移动一位，越过尾部后返回到数组头部
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rear = (rear + 1) % capacity();
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}
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/* 出队 */
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int poll() {
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// 删除头结点
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if (empty())
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throw out_of_range("队列为空");
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int num = nums[front];
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// 队头指针向后移动，越过尾部后返回到数组头部
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front = (front + 1) % capacity();
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return num;
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}
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/* 访问队首元素 */
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int peek() {
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// 删除头结点
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if (empty())
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throw out_of_range("队列为空");
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return nums[front];
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}
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/* 访问指定索引元素 */
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int get(int index) {
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if (index >= size())
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throw out_of_range("索引越界");
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return nums[(front + index) % capacity()];
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}
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/* 将数组转化为 Vector 并返回 */
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vector<int> toVector() {
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int siz = size();
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int cap = capacity();
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// 仅转换有效长度范围内的列表元素
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vector<int> arr(siz);
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for (int i = 0, j = front; i < siz; i++, j++) {
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arr[i] = nums[j % cap];
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}
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return arr;
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}
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};
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/* Driver Code */
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int main() {
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/* 初始化队列 */
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int capacity = 10;
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ArrayQueue* queue = new ArrayQueue(capacity);
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/* 元素入队 */
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queue->offer(1);
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queue->offer(3);
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queue->offer(2);
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queue->offer(5);
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queue->offer(4);
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cout << "队列 queue = ";
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PrintUtil::printVector(queue->toVector());
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/* 访问队首元素 */
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int peek = queue->peek();
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cout << "队首元素 peek = " << peek << endl;
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/* 访问指定索引元素 */
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int num = queue->get(2);
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cout << "队列第 3 个元素为 num = " << num << endl;
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/* 元素出队 */
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int poll = queue->poll();
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cout << "出队元素 poll = " << poll << "，出队后 queue = ";
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PrintUtil::printVector(queue->toVector());
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/* 获取队列的长度 */
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int size = queue->size();
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cout << "队列长度 size = " << size << endl;
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/* 判断队列是否为空 */
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bool empty = queue->empty();
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cout << "队列是否为空 = " << empty << endl;
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/* 测试环形数组 */
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for (int i = 0; i < 10; i++) {
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queue->offer(i);
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queue->poll();
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cout << "第 " << i << " 轮入队 + 出队后 queue = ";
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PrintUtil::printVector(queue->toVector());
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}
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return 0;
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}
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