1.用队列实现栈
225. 用队列实现栈 - 力扣（LeetCode）
typedef int QDatatype;
typedef struct QueueNode
{struct QueueNode *next;QDatatype data;
}QNode;typedef struct Queue
{QNode* head;QNode* tail;QDatatype size;
}Que;typedef struct
{Que q1;Que q2;
} MyStack;void QueueInit(Que* pq);
void QueueDestroy(Que* pq);void QueuePush(Que* pq, QDatatype x);
void QueuePop(Que* pq);
int QueueSize(Que* pq);
bool QueueEmpty(Que* pq);QDatatype QueueFront(Que* pq);//队头数据
QDatatype QueueBack(Que* pq);//队尾数据void QueueInit(Que* pq)
{assert(pq);pq->head = pq->tail = NULL;pq->size = 0;
}void QueueDestroy(Que* pq)
{assert(pq);QNode* cur = pq->head;while (cur){QNode* next = cur->next;free(cur);cur = next;}pq->head = pq->tail = NULL;pq->size = 0;
}void QueuePush(Que* pq, QDatatype x)
{QNode* newnode = (QNode*)malloc(sizeof(QNode));if (newnode==NULL){perror("malloc fail");return;}newnode->data = x;newnode->next = NULL;if (pq->head == NULL){assert(pq->tail == NULL);pq->head = pq->tail = newnode;}else{pq->tail->next = newnode;pq->tail = newnode;}pq->size++;
}void QueuePop(Que* pq)
{assert(pq);assert(pq->head != NULL);QNode* oldhead = pq->head;pq->head = pq->head->next;free(oldhead);if (pq->head == NULL){pq->tail = NULL;}pq->size--;
}int QueueSize(Que* pq)
{assert(pq);return pq->size;
}bool QueueEmpty(Que* pq)
{assert(pq);return pq->size == 0;
}QDatatype QueueFront(Que* pq)
{assert(pq);assert(!QueueEmpty(pq));return pq->head->data;
}QDatatype QueueBack(Que* pq)
{assert(pq);assert(!QueueEmpty(pq));return pq->tail->data;
}MyStack* myStackCreate()
{MyStack*pst=(MyStack*)malloc(sizeof(MyStack));if(pst==NULL){perror("malloc fail");return NULL;}QueueInit(&pst->q1);QueueInit(&pst->q2);return pst;
}void myStackPush(MyStack* obj, int x)
{if(!QueueEmpty(&obj->q1)){QueuePush(&obj->q1,x);}else{QueuePush(&obj->q2,x);}
}int myStackPop(MyStack* obj)
{assert(obj != NULL);Que* emptyQ = NULL;Que* noneemptyQ = NULL;// 确定哪个队列是非空的if (!QueueEmpty(&obj->q1) && QueueEmpty(&obj->q2)) {noneemptyQ = &obj->q1;emptyQ = &obj->q2;} else if (QueueEmpty(&obj->q1) && !QueueEmpty(&obj->q2)) {noneemptyQ = &obj->q2;emptyQ = &obj->q1;} else {// 两个队列都为空，栈为空return -1; }// 将非空队列的元素（除最后一个外）移到空队列while (QueueSize(noneemptyQ) > 1) {QueuePush(emptyQ, QueueFront(noneemptyQ));QueuePop(noneemptyQ);}// 最后一个元素是栈顶int top = QueueFront(noneemptyQ);QueuePop(noneemptyQ);return top;
}int myStackTop(MyStack* obj)
{if(!QueueEmpty(&obj->q1)){return QueueBack(&obj->q1);}else{return QueueBack(&obj->q2);}
}bool myStackEmpty(MyStack* obj)
{return(QueueEmpty(&obj->q1)&&QueueEmpty(&obj->q2));
}void myStackFree(MyStack* obj)
{QueueDestroy(&obj->q1);QueueDestroy(&obj->q2);free(obj);
}2.用栈实现队列
232. 用栈实现队列 - 力扣（LeetCode）
typedef int STDataType;typedef struct Stack
{int* a;int top;int capacity;
}ST;typedef struct
{ST Popst;ST Pushst;
} MyQueue;void STInit(ST* ps);
void STDestroy(ST* ps);void STPush(ST* ps,STDataType x);
void STPop(ST* ps);
int STSize(ST* ps);
bool STEmpty(ST* ps);STDataType STTop(ST* ps);void STInit(ST* ps)
{assert(ps);ps->a = (STDataType*)malloc(sizeof(STDataType) * 4);if (ps->a == NULL){perror("malloc fail");return;}ps->capacity = 4;ps->top = 0;//top是栈顶元素的下一位置}void STDestroy(ST* ps)
{assert(ps);free(ps->a);ps->a = NULL;ps->capacity = 0;ps->top = 0;
}void STPush(ST* ps, STDataType x)
{assert(ps);if (ps->top == ps->capacity){STDataType*tmp = (STDataType*)realloc(ps->a,sizeof(STDataType) * ps->capacity*2);if (tmp == NULL){perror("malloc fail");return;}ps->a = tmp;ps->capacity *= 2;}ps->a[ps->top] = x;ps->top++;
}void STPop(ST* ps)
{assert(ps);assert(!STEmpty(ps));ps->top--;
}int STSize(ST* ps)
{assert(ps);return ps->top;
}
bool STEmpty(ST* ps)
{assert(ps);return ps->top == 0;
}STDataType STTop(ST* ps)
{assert(ps);assert(!STEmpty(ps));return ps->a[ps->top - 1];
}MyQueue* myQueueCreate()
{MyQueue*obj=(MyQueue*)malloc(sizeof(MyQueue));if(obj==NULL){perror("malloc fail");return NULL;}STInit(&obj->Pushst);STInit(&obj->Popst);return obj;
}void myQueuePush(MyQueue* obj, int x)
{STPush(&obj->Pushst,x);
}int myQueuePeek(MyQueue* obj)
{if(STEmpty(&obj->Popst)){while(!STEmpty(&obj->Pushst)){STPush(&obj->Popst,STTop(&obj->Pushst));STPop(&obj->Pushst);}}return STTop(&obj->Popst);
}int myQueuePop(MyQueue* obj)
{int front=myQueuePeek(obj);STPop(&obj->Popst);return front;
}bool myQueueEmpty(MyQueue* obj)
{return(STEmpty(&obj->Pushst)&&STEmpty(&obj->Popst));
}void myQueueFree(MyQueue* obj)
{STDestroy(&obj->Pushst);STDestroy(&obj->Popst);free(obj);
}3.设计循环队列
622. 设计循环队列 - 力扣（LeetCode）
typedef struct {int*a;int k;int front;int rear;
} MyCircularQueue;MyCircularQueue* myCircularQueueCreate(int k) {MyCircularQueue*obj=(MyCircularQueue*)malloc(sizeof(MyCircularQueue));obj->front=obj->rear=0;obj->a=(int*)malloc(sizeof(int)*(k+1));obj->k=k;return obj;
}bool myCircularQueueIsEmpty(MyCircularQueue* obj) {return obj->front==obj->rear;
}bool myCircularQueueIsFull(MyCircularQueue* obj) {return (obj->rear+1)%(obj->k+1)==obj->front;
}bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {if(myCircularQueueIsFull(obj))return false;obj->a[obj->rear++]=value;obj->rear%=(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;elsereturn obj->a[obj->front];
}int myCircularQueueRear(MyCircularQueue* obj) {if(myCircularQueueIsEmpty(obj))return -1;elsereturn obj->a[(obj->rear-1+obj->k+1)%(obj->k+1)];
}void myCircularQueueFree(MyCircularQueue* obj) {free(obj->a);free(obj);
}
