225. 用队列实现栈 - 力扣（LeetCode）

Queue.h

#pragma once
#include<stdlib.h>
#include<assert.h>
#include<stdbool.h>typedef int QDataType;typedef struct QNode
{QDataType data;struct QNode* next;
} QNode;typedef struct Queue
{QNode* head;QNode* tail;int size;
} Queue;Queue* QueueCreate();
void QueueDestroy(Queue* q);void QueuePush(Queue* q, QDataType x);
QDataType QueuePop(Queue* q);QDataType QueueFront(Queue* q);
QDataType QueueBack(Queue* q);int QueueSize(Queue* q);
bool QueueEmpty(Queue* q);

Queue.c

#include"Queue.h"Queue* QueueCreate()
{Queue* q = (Queue*)malloc(sizeof(Queue));if (NULL == q){perror("malloc failed");exit(-1);}q->head = q->tail = NULL;q->size = 0;return q;
}void QueueDestroy(Queue* q)
{assert(q);while (!QueueEmpty(q))QueuePop(q);free(q);
}void QueuePush(Queue* q, QDataType x)
{assert(q);QNode* newnode = (QNode*)malloc(sizeof(QNode));if (NULL == newnode){perror("malloc failed");exit(-1);}newnode->data = x;newnode->next = NULL;if (QueueEmpty(q))q->head = q->tail = newnode;else{q->tail->next = newnode;q->tail = newnode;}++(q->size);
}QDataType QueuePop(Queue* q)
{assert(q);assert(!QueueEmpty(q));QDataType ret = q->head->data;QNode* newhead = q->head->next;free(q->head);q->head = newhead;if (NULL == newhead)q->tail = NULL;--(q->size);return ret;
}QDataType QueueFront(Queue* q)
{assert(q);assert(!QueueEmpty(q));return q->head->data;
}QDataType QueueBack(Queue* q)
{assert(q);assert(!QueueEmpty(q));return q->tail->data;
}int QueueSize(Queue* q)
{assert(q);return q->size;
}bool QueueEmpty(Queue* q)
{assert(q);return !(q->size);
}

MyStack.h

#pragma once
#include"Queue.h"typedef struct MyStack
{Queue* qa;Queue* qb;
} MyStack;MyStack* myStackCreate();void myStackPush(MyStack* st, int x);QDataType myStackPop(MyStack* st);QDataType myStackTop(MyStack* st);bool myStackEmpty(MyStack* st);void myStackFree(MyStack* st);

MyStack.c

#include "MyStack.h"MyStack* myStackCreate()
{MyStack* st = (MyStack*)malloc(sizeof(MyStack));if (NULL == st){perror("malloc failed");exit(-1);}st->qa = QueueCreate();st->qb = QueueCreate();return st;
}void myStackPush(MyStack* st, QDataType x)
{assert(st);if (QueueEmpty(st->qb))QueuePush(st->qa, x);elseQueuePush(st->qa, x);
}QDataType myStackPop(MyStack* st)
{assert(st);assert(!myStackEmpty(st));Queue* empty = st->qa;Queue* noempty = st->qb;if (!QueueEmpty(st->qa)){empty = st->qb;noempty = st->qa;}QDataType ret = noempty->tail->data;while (QueueSize(noempty) > 1){QDataType ret = QueuePop(noempty);QueuePush(empty, ret);}QueuePop(noempty);return ret;
}QDataType myStackTop(MyStack* st)
{assert(st);assert(!myStackEmpty(st));if (QueueEmpty(st->qb))return st->qa->tail->data;elsereturn st->qb->tail->data;
}bool myStackEmpty(MyStack* st)
{return (QueueEmpty(st->qa) && QueueEmpty(st->qb));
}void myStackFree(MyStack* st)
{QueueDestroy(st->qa);QueueDestroy(st->qb);free(st);
}

test.c

#include<stdio.h>
#include "MyStack.h"static void Qprint(Queue* q)
{assert(q);QNode* cur = q->head;printf("head<-");while (cur){printf("%d<-", cur->data);cur = cur->next;}printf("tail\n");
}void test1()
{MyStack* st = myStackCreate();myStackPush(st, 1);myStackPush(st, 2);printf("top = %d\n", myStackTop(st));myStackPush(st, 3);printf("qa:"); Qprint(st->qa); printf("qb:"); Qprint(st->qb);printf("top = %d\n", myStackTop(st));myStackPush(st, 4);printf("qa:"); Qprint(st->qa); printf("qb:"); Qprint(st->qb);printf("top = %d\n", myStackTop(st));myStackPop(st);printf("qa:"); Qprint(st->qa); printf("qb:"); Qprint(st->qb);myStackPop(st);printf("qa:"); Qprint(st->qa); printf("qb:"); Qprint(st->qb);printf("top = %d\n", myStackTop(st));myStackFree(st);
}int main()
{test1();return 0;
}