mirror of
https://github.com/krahets/hello-algo.git
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132 lines
3.2 KiB
C
132 lines
3.2 KiB
C
/**
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* File: array_queue.c
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* Created Time: 2023-01-28
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* Author: Zero (glj0@outlook.com)
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*/
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#include "../utils/common.h"
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/* 基于环形数组实现的队列 */
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struct arrayQueue {
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int *nums; // 用于存储队列元素的数组
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int front; // 队首指针，指向队首元素
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int queSize; // 尾指针，指向队尾 + 1
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int queCapacity; // 队列容量
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};
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typedef struct arrayQueue arrayQueue;
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/* 构造函数 */
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arrayQueue *newArrayQueue(int capacity) {
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arrayQueue *queue = (arrayQueue *)malloc(sizeof(arrayQueue));
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// 初始化数组
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queue->queCapacity = capacity;
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queue->nums = (int *)malloc(sizeof(int) * queue->queCapacity);
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queue->front = queue->queSize = 0;
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return queue;
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}
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/* 析构函数 */
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void delArrayQueue(arrayQueue *queue) {
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free(queue->nums);
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queue->queCapacity = 0;
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}
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/* 获取队列的容量 */
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int capacity(arrayQueue *queue) {
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return queue->queCapacity;
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}
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/* 获取队列的长度 */
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int size(arrayQueue *queue) {
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return queue->queSize;
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}
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/* 判断队列是否为空 */
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bool empty(arrayQueue *queue) {
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return queue->queSize == 0;
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}
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/* 访问队首元素 */
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int peek(arrayQueue *queue) {
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assert(size(queue) != 0);
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return queue->nums[queue->front];
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}
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/* 入队 */
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void push(arrayQueue *queue, int num) {
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if (size(queue) == capacity(queue)) {
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printf("队列已满\r\n");
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return;
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}
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// 计算队尾指针，指向队尾索引 + 1
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// 通过取余操作，实现 rear 越过数组尾部后回到头部
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int rear = (queue->front + queue->queSize) % queue->queCapacity;
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// 将 num 添加至队尾
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queue->nums[rear] = num;
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queue->queSize++;
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}
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/* 出队 */
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void pop(arrayQueue *queue) {
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int num = peek(queue);
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// 队首指针向后移动一位，若越过尾部则返回到数组头部
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queue->front = (queue->front + 1) % queue->queCapacity;
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queue->queSize--;
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}
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/* 打印队列 */
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void printArrayQueue(arrayQueue *queue) {
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int arr[queue->queSize];
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// 拷贝
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for (int i = 0, j = queue->front; i < queue->queSize; i++, j++) {
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arr[i] = queue->nums[j % queue->queCapacity];
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}
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printArray(arr, queue->queSize);
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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 = newArrayQueue(capacity);
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/* 元素入队 */
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push(queue, 1);
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push(queue, 3);
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push(queue, 2);
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push(queue, 5);
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push(queue, 4);
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printf("队列 queue = ");
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printArrayQueue(queue);
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/* 访问队首元素 */
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int peekNum = peek(queue);
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printf("队首元素 peek = %d\r\n", peekNum);
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/* 元素出队 */
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pop(queue);
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printf("出队元素 pop = %d，出队后 queue = ", peekNum);
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printArrayQueue(queue);
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/* 获取队列的长度 */
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int queueSize = size(queue);
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printf("队列长度 size = %d\r\n", queueSize);
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/* 判断队列是否为空 */
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bool isEmpty = empty(queue);
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printf("队列是否为空 = %s\r\n", isEmpty ? "true" : "false");
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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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push(queue, i);
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pop(queue);
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printf("第 %d 轮入队 + 出队后 queue = ", i);
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printArrayQueue(queue);
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}
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// 释放内存
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delArrayQueue(queue);
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return 0;
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}
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