本文主要是介绍用队列实现栈（力扣第225题），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
#include "stdio.h"
#include "stdbool.h"
#include "string.h"
#include "stdlib.h"
#include "assert.h"//初始化队列
typedef int QueueDataType;typedef struct queue {QueueDataType val;struct queue* next;
}Qnode;typedef struct Queue {Qnode* phead;//队头Qnode* ptail;//队尾int size;//队列中的有效数据
}Queue;//初始化队
void QueueInit(Queue* pq);//入队
void QueuePush(Queue* pq,QueueDataType x);//出队
void QueuePop(Queue* pq);//获取队首元素
QueueDataType QueueFront(Queue* pq);//获取队尾元素
QueueDataType QueueBack(Queue* pq);//获取队列有效个数
int QueueSize(Queue* pq);//判断队列是否为空，为空返回1，非空返回0
bool QueueEmpty(Queue* pq);//打印队列
void QueuePrint(Queue* pq);//销毁队列
void QueueDestory(Queue* pq);#define _CRT_SECURE_NO_WARNINGS 1//初始化队
void QueueInit(Queue* pq)
{assert(pq);pq->size=0;pq->phead=pq->ptail=NULL;
}//入队
void QueuePush(Queue* pq, QueueDataType x)
{assert(pq);assert(pq);Qnode* newnode = (Qnode*)malloc(sizeof(Qnode));if (newnode == NULL){printf("malloc fail\n");exit(-1);}pq->size++;newnode->val = x;newnode->next = NULL;if (pq->phead == NULL){pq->phead = pq->ptail = newnode;}else{pq->ptail->next = newnode;pq->ptail = newnode;}
}//出队
void QueuePop(Queue* pq) {assert(pq);Qnode* next = pq->phead->next;free(pq->phead);pq->size--;pq->phead = next;
}//获取队首元素
QueueDataType QueueFront(Queue* pq) {assert(pq);assert(pq->size > 0);assert(pq->phead);return pq->phead->val;
}//获取队尾元素
QueueDataType QueueBack(Queue* pq) {assert(pq);assert(pq->ptail);assert(pq->size > 0);return pq->ptail->val;
}//获取队列有效个数
int QueueSize(Queue* pq) {assert(pq);return pq->size;
}//判断队列是否为空，为空返回1，非空返回0
bool QueueEmpty(Queue* pq) {assert(pq);return pq->size == 0 ? 1 : 0;
}//打印队列
void QueuePrint(Queue* pq) {assert(pq);assert(pq->phead);while (!QueueEmpty(pq)){printf("%d\n", pq->phead->val);QueuePop(pq);}
}//销毁队列
void QueueDestory(Queue* pq) {assert(pq);Qnode* cur = pq->phead;while (cur) {Qnode* next = cur->next;free(cur);cur = next;}pq->phead = pq->ptail = NULL;
}typedef struct {Queue pq1;Queue pq2;} MyStack;MyStack* myStackCreate() {MyStack* ST=(MyStack*)malloc(sizeof(MyStack));QueueInit(&ST->pq1);QueueInit(&ST->pq2);return ST;
}void myStackPush(MyStack* obj, int x) {if(QueueEmpty(&obj->pq1)){QueuePush(&obj->pq2,x);}else{QueuePush(&obj->pq1,x);}
}int myStackPop(MyStack* obj) {if(QueueEmpty(&obj->pq1)){while((&obj->pq2)->phead!=(&obj->pq2)->ptail){QueuePush(&obj->pq1,QueueFront(&obj->pq2));QueuePop(&obj->pq2);}int vala=QueueFront(&obj->pq2);QueuePop(&obj->pq2);return vala;}if(QueueEmpty(&obj->pq2)){while((&obj->pq1)->phead!=(&obj->pq1)->ptail){QueuePush(&obj->pq2,QueueFront(&obj->pq1));QueuePop(&obj->pq1);}}int valb=QueueFront(&obj->pq1);QueuePop(&obj->pq1);return valb;
}int myStackTop(MyStack* obj) {if(QueueEmpty(&obj->pq1)){return (&obj->pq2)->ptail->val;}return (&obj->pq1)->ptail->val;
}bool myStackEmpty(MyStack* obj) {if(QueueEmpty(&obj->pq1)&&QueueEmpty(&obj->pq2)){return true;}return false;
}void myStackFree(MyStack* obj) {Qnode* cur1 = (&obj->pq1)->phead;while(cur1){Qnode* next=cur1->next;free(cur1);cur1=next;}(&obj->pq1)->phead=(&obj->pq1)->ptail=NULL;Qnode* cur2 = (&obj->pq2)->phead;while(cur2){Qnode* next=cur2->next;free(cur2);cur2=next;}(&obj->pq2)->phead=(&obj->pq2)->ptail=NULL;(&obj->pq2)->phead=(&obj->pq2)->ptail=NULL;free(obj);obj=NULL;
}/*** Your MyStack struct will be instantiated and called as such:* MyStack* obj = myStackCreate();* myStackPush(obj, x);* int param_2 = myStackPop(obj);* int param_3 = myStackTop(obj);* bool param_4 = myStackEmpty(obj);* myStackFree(obj);
*/
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