hello-algo/codes/c/chapter_stack_and_queue/array_queue.c
2023-04-17 22:15:06 +08:00

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/**
* File: array_queue.c
* Created Time: 2023-01-28
* Author: Zero (glj0@outlook.com)
*/
#include "../include/include.h"
/* 基于环形数组形成的队列 */
struct ArrayQueue {
int *nums; // 用于存储队列元素的数组
int front; // 队首指针,指向队首元素
int queSize; // 尾指针,指向队尾 + 1
int queCapacity; // 队列容量
};
typedef struct ArrayQueue ArrayQueue;
/* 构造方法 */
ArrayQueue *newArrayQueue(int capacity) {
ArrayQueue *queue = (ArrayQueue *)malloc(sizeof(ArrayQueue));
// 初始化数组
queue->queCapacity = capacity;
queue->nums = (int *)malloc(sizeof(int) * queue->queCapacity);
queue->front = queue->queSize = 0;
return queue;
}
/* 析构方法 */
void delArrayQueue(ArrayQueue *queue) {
free(queue->nums);
queue->queCapacity = 0;
}
/* 获取队列的容量 */
int capacity(ArrayQueue *queue) {
return queue->queCapacity;
}
/* 获取队列的长度 */
int size(ArrayQueue *queue) {
return queue->queSize;
}
/* 判断队列是否为空 */
bool empty(ArrayQueue *queue) {
return queue->queSize == 0;
}
/* 访问队首元素 */
int peek(ArrayQueue *queue) {
assert(size(queue) != 0);
return queue->nums[queue->front];
}
/* 入队 */
void push(ArrayQueue *queue, int num) {
if (size(queue) == capacity(queue)) {
printf("队列已满\r\n");
return;
}
// 计算队尾指针,指向队尾索引 + 1
// 通过取余操作,实现 rear 越过数组尾部后回到头部
int rear = (queue->front + queue->queSize) % queue->queCapacity;
// 将 num 添加至队尾
queue->nums[rear] = num;
queue->queSize++;
}
/* 出队 */
void pop(ArrayQueue *queue) {
int num = peek(queue);
// 队首指针向后移动一位,若越过尾部则返回到数组头部
queue->front = (queue->front + 1) % queue->queCapacity;
queue->queSize--;
}
/* 打印基于环形数组形成的队列 */
void printArrayQueue(ArrayQueue *queue) {
int arr[queue->queSize];
// 拷贝
for (int i = 0, j = queue->front; i < queue->queSize; i++, j++) {
arr[i] = queue->nums[j % queue->queCapacity];
}
printArray(arr, queue->queSize);
}
/* Driver Code */
int main() {
/* 初始化队列 */
int capacity = 10;
ArrayQueue *queue = newArrayQueue(capacity);
/* 元素入队 */
push(queue, 1);
push(queue, 3);
push(queue, 2);
push(queue, 5);
push(queue, 4);
printf("队列 queue = ");
printArrayQueue(queue);
/* 访问队首元素 */
int peekNum = peek(queue);
printf("队首元素 peek = %d\r\n", peekNum);
/* 元素出队 */
pop(queue);
printf("出队元素 pop = %d出队后 queue = ", peekNum);
printArrayQueue(queue);
/* 获取队列的长度 */
int queueSize = size(queue);
printf("队列长度 size = %d\r\n", queueSize);
/* 判断队列是否为空 */
bool isEmpty = empty(queue);
printf("队列是否为空 = %s\r\n", isEmpty ? "true" : "false");
/* 测试环形数组 */
for (int i = 0; i < 10; i++) {
push(queue, i);
pop(queue);
printf("第 %d 轮入队 + 出队后 queue = ", i);
printArrayQueue(queue);
}
// 释放内存
delArrayQueue(queue);
return 0;
}