【622. 设计循环队列】

一、题目描述

二、提供方便走读代码的图

三、题目代码

顺序表实现

typedef struct {
    int* a;
    int front;
    int tail;
    int k;
} MyCircularQueue;
bool myCircularQueueIsFull(MyCircularQueue* obj);
bool myCircularQueueIsEmpty(MyCircularQueue* obj);
MyCircularQueue* myCircularQueueCreate(int k) {
    MyCircularQueue* cq = (MyCircularQueue*)malloc(sizeof(MyCircularQueue));
    cq->a = (int*)malloc(sizeof(int)*(k+1));
    cq->front = cq->tail = 0;
    cq->k = k;
    return cq;
}

bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {
    if(myCircularQueueIsFull(obj))return false;
    obj->a[obj->tail] = value;
    obj->tail++;
    obj->tail %= (obj->k+1);
    return true;
}

bool myCircularQueueDeQueue(MyCircularQueue* obj) {
    if(myCircularQueueIsEmpty(obj))return false;
    obj->front++;
    obj->front %= (obj->k+1);
    return true;
}

int myCircularQueueFront(MyCircularQueue* obj) {
    if(myCircularQueueIsEmpty(obj))return -1;
    return obj->a[obj->front];
}

int myCircularQueueRear(MyCircularQueue* obj) {
    if(myCircularQueueIsEmpty(obj))return -1;
    if(obj->tail == 0)
    return obj->a[obj->k];
    else
    return obj->a[obj->tail-1];
    //int i = (obj->tail+obj->k)%(obj->k+1);
    //return obj->a[i];
}

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

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

void myCircularQueueFree(MyCircularQueue* obj) {
     free(obj->a);
     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);
*/

链表实现

typedef struct Queuenode{
    struct Queuenode* next;
    int data;
} Queuenode;
typedef struct {
    struct Queuenode* head;
    struct Queuenode* tail;
} MyCircularQueue;
bool myCircularQueueIsFull(MyCircularQueue* obj);
bool myCircularQueueIsEmpty(MyCircularQueue* obj);
MyCircularQueue* myCircularQueueCreate(int k) {
    MyCircularQueue* cq = (MyCircularQueue*)malloc(sizeof(MyCircularQueue));
    Queuenode* newnode = (Queuenode*)malloc(sizeof(Queuenode));
    newnode->next=newnode;
    cq->head = cq->tail = newnode;
    for(int i=0 ; i < k; i++)
    {
        Queuenode* knode = (Queuenode*)malloc(sizeof(Queuenode));
        cq->tail->next=knode;
        knode->next=cq->head;
        cq->tail=knode;
    }
     cq->tail=cq->head;
     return cq;
}

bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {
    if(myCircularQueueIsFull(obj))return false;
    obj->tail->data = value;
    obj->tail = obj->tail->next;
    return true;
}

bool myCircularQueueDeQueue(MyCircularQueue* obj) {
    if(myCircularQueueIsEmpty(obj))return false;
    obj->head = obj->head->next;
    return true;
}

int myCircularQueueFront(MyCircularQueue* obj) {
   if(myCircularQueueIsEmpty(obj))return -1;
   return obj->head->data;
}

int myCircularQueueRear(MyCircularQueue* obj) {
   if(myCircularQueueIsEmpty(obj))return -1;
   Queuenode* cur = obj->head;
   while(cur->next != obj->tail)
   {
       cur = cur->next;
   }
   return cur->data;
}

bool myCircularQueueIsEmpty(MyCircularQueue* obj) {
    return obj->head == obj->tail;
}

bool myCircularQueueIsFull(MyCircularQueue* obj) {
    return obj->tail->next == obj->head;
}

void myCircularQueueFree(MyCircularQueue* obj) {
   Queuenode* cur = obj->head->next;
   Queuenode* head = obj->head;
   Queuenode* p = NULL;
   free(obj->head);
   while(cur != head)
   {
       p = cur;
       cur = cur->next;
       free(p);
   }
   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);
*/