leetcode 622

typedef struct {
  int * data;
  int front;
  int rear;
  int maxsize;
} MyCircularQueue;

MyCircularQueue* myCircularQueueCreate(int k) {
  MyCircularQueue *q =
	  (MyCircularQueue *)malloc(sizeof(MyCircularQueue));
  /* 需要多留一个空位 */
  q->data = (int*)malloc(sizeof(int) * (k + 1));
  q->front = 0;
  q->rear = 0;
  q->maxsize = k + 1;
  return q;
}

bool myCircularQueueIsEmpty(MyCircularQueue* obj) {
  return obj->front == obj->rear;  
}

bool myCircularQueueIsFull(MyCircularQueue* obj) {
  return (obj->rear + 1) % obj->maxsize == obj->front;
}

bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {
  /* 入队: 核心在于 rear++ */
  if (obj == NULL || myCircularQueueIsFull(obj))
    return false;
  obj->data[obj->rear] = value;
  obj->rear = (obj->rear + 1) % obj->maxsize;
  return true;
}

bool myCircularQueueDeQueue(MyCircularQueue* obj) {
  /* 出队: 核心在于 front++ */
  if (obj == NULL || myCircularQueueIsEmpty(obj))
    return false;
  obj->front = (obj->front + 1) % obj->maxsize;
  return true;
}

int myCircularQueueFront(MyCircularQueue* obj) {
  /* front 位置的数值 */
  if(myCircularQueueIsEmpty(obj)) return -1;
  return obj->data[obj->front];
}

int myCircularQueueRear(MyCircularQueue* obj) {
  /* rear 位置的数值 */
  if(myCircularQueueIsEmpty(obj)) return -1;
  int index = (obj->rear - 1 + obj->maxsize) % obj->maxsize;
  return obj->data[index];
}

void myCircularQueueFree(MyCircularQueue* obj) {
  if(obj == NULL) return;
  free(obj->data);
  obj->data = NULL;
  free(obj);
  obj = NULL;
  return;
}

/**
 * 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);
*/