c语言刷leetcode——常见数据结构实现

• 622. 设计循环队列
• 641. 设计循环双端队列

622. 设计循环队列

typedef struct {
    int *queue;
    int front;
    int rear;
    int capacity;

} MyCircularQueue;


MyCircularQueue* myCircularQueueCreate(int k) 
{
    MyCircularQueue *obj = malloc(sizeof(MyCircularQueue));
    obj->capacity = k + 1; // 多出1个空间，作为哨兵，用来区别队列NULL与EMPTY的区别
    obj->front = 0;
    obj->rear = 0;
    obj->queue = malloc(sizeof(int) * obj->capacity); 
    return obj;
}

bool myCircularQueueIsEmpty(MyCircularQueue* obj) 
{
    return obj->front == obj->rear; // k = 3时，rear和front的取值: 0, 1, 2, 3
}

bool myCircularQueueIsFull(MyCircularQueue* obj) 
{
    return (obj->rear + 1) % obj->capacity == obj->front;// k = 3时，比如满的条件: rear = 3, front = 0; rear = 2, front = 3; ...
}

// 添加元素，尾插，rear++，注意循环
bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) 
{
    if (myCircularQueueIsFull(obj)) return false;

    obj->queue[obj->rear] = value;
    // mod cap，循环；比如cap = k + 1 = 4, 则rear的取值: 0, 1, 2, 3
    obj->rear = (obj->rear + 1) % obj->capacity; 
    return true;
}

// 删除元素，头删，front++，注意循环
bool myCircularQueueDeQueue(MyCircularQueue* obj) 
{
    if (myCircularQueueIsEmpty(obj)) return false;

    // 比如cap = k + 1 = 4, 则front的取值: 0, 1, 2, 3
    obj->front = (obj->front + 1) % obj->capacity;
    return true;
}

int myCircularQueueFront(MyCircularQueue* obj) 
{
    if (myCircularQueueIsEmpty(obj)) return -1;

    return obj->queue[obj->front];
}

int myCircularQueueRear(MyCircularQueue* obj) 
{
    if (myCircularQueueIsEmpty(obj)) return -1;

    // obj->rear - 1 + obj->capacity，必须要 + obj->capacity，防止obj->rear - 1为负数
    return obj->queue[(obj->rear - 1 + obj->capacity) % obj->capacity];
}

void myCircularQueueFree(MyCircularQueue* obj) 
{
    free(obj->queue);
    free(obj);
}

/**
 * Your MyCircularQueue struct will be instantiated and called as such:
 * MyCircularQueue* obj = myCircularQueueCreate(k);
 * bool param_1 = myCircularQueueEnQueue(obj, value);
 
 * bool param_2 = myCircularQueueDeQueue(obj);
 
 * int param_3 = myCircularQueueFront(obj);
 
 * int param_4 = myCircularQueueRear(obj);
 
 * bool param_5 = myCircularQueueIsEmpty(obj);
 
 * bool param_6 = myCircularQueueIsFull(obj);
 
 * myCircularQueueFree(obj);
*/

641. 设计循环双端队列