C语言设计题练习4-设计循环队列

题目

622. 设计循环队列

代码

链表实现

typedef struct tagListNode {
    int val;
    struct tagListNode *next;
} ListNode;

typedef struct {
    ListNode *head;
    ListNode *tail;
    int capacity;
    int size;
} MyCircularQueue;

MyCircularQueue *myCircularQueueCreate(int k)
{
    MyCircularQueue *obj = (MyCircularQueue *)malloc(sizeof(MyCircularQueue));
    obj->capacity = k;
    obj->size = 0;
    obj->head = NULL;
    obj->tail = NULL;
    return obj;
}

bool myCircularQueueEnQueue(MyCircularQueue *obj, int value)
{
    if (obj->size == obj->capacity) {
        return false;
    }
    ListNode *node = (ListNode *)malloc(sizeof(ListNode));
    node->val = value;
    node->next = NULL;
    if (!obj->head) {
        obj->head = node;
        obj->tail = node;
    } else {
        obj->tail->next = node;
        obj->tail = node;
    }
    obj->size++;
    return true;
}

bool myCircularQueueDeQueue(MyCircularQueue *obj)
{
    if (obj->size == 0) {
        return false;
    }
    ListNode *node = obj->head;
    obj->head = node->next;
    obj->size--;
    free(node);
    return true;
}

int myCircularQueueFront(MyCircularQueue *obj)
{
    if (obj->size == 0) {
        return -1;
    }
    return obj->head->val;
}

int myCircularQueueRear(MyCircularQueue *obj)
{
    if (obj->size == 0) {
        return -1;
    }
    return obj->tail->val;
}

bool myCircularQueueIsEmpty(MyCircularQueue *obj)
{
    return obj->size == 0;
}

bool myCircularQueueIsFull(MyCircularQueue *obj)
{
    return obj->size == obj->capacity;
}

void myCircularQueueFree(MyCircularQueue *obj)
{
    for (ListNode *cur = obj->head; cur;) {
        ListNode *node = cur;
        cur = cur->next;
        free(node);
    }
    free(obj);
}