两个队列实现一个栈

核心思想：模拟出栈的后进先出操作
创建queue1和queue2，入栈时选择一个非空队列执行入队列操作（若两个队列都为空，则随机选择一个队列），出栈时需要先从非空队列queue1把数依次进入空数列queue2，直到queue1中到最后一个数为止，然后将queue1中的数出队列，模拟出栈的后进先出操作。

代码模拟
Stackby_two_queue.h

#pragma oncetypedef char DataType2;typedef struct Queue
{DataType2* queue_data;int head;int tail;int size;int capacity;
}Queue;typedef struct Stack
{Queue queue1;Queue queue2;//栈中有效元素个数int size;
}Stack;//栈的初始化
void StackInit(Stack *stack,int vector_capacity);
//栈的销毁
void StackDestory(Stack* stack);
//入栈
void StackPush(Stack* stack, DataType2 value);
//出栈
void StackPop(Stack* stack);
//取栈顶元素
DataType2 StackGetTop(Stack* stack);

Stackby_two_queue.c

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "Stackby_two_queue.h"void QueueInit(Queue* queue, int vector_capacity)
{if (queue == NULL){assert(0);return -1;}queue->capacity = vector_capacity;queue->queue_data = (DataType2*)malloc(sizeof(DataType2)*queue->capacity);queue->size = 0;queue->head = 0;queue->tail = 0;
}void QueueDestory(Queue* queue)
{if (queue == NULL){assert(0);return -1;}free(queue->queue_data);queue->queue_data = NULL;queue->size = 0;queue->head = 0;queue->tail = 0;queue->capacity = 0;
}void QueuePush(Queue* queue,DataType2 value)
{if (queue == NULL){assert(0);return -1;}if (queue->size >= queue->capacity){return ;}queue->queue_data[queue->tail++] = value;queue->size++;if (queue->tail > queue->capacity){queue->tail = 0;}
}void QueuePop(Queue* queue)
{if (queue == NULL){assert(0);return -1;}if (queue->size == 0){return ; }if (queue->head >= queue->capacity){queue->head = 0;}queue->head++;queue->size--;if (queue->size == 0){queue->head = 0;queue->tail = 0;}
}
//取队首元素
DataType2 QueueGetTop(Queue* queue)
{if (queue == NULL){assert(0);return -1;}if (queue->size == 0){return ;}return queue->queue_data[queue->head];
}//打印整个队列
void PrintQueue(Queue* queue)
{if (queue == NULL){assert(0);return -1;}if (queue->size == 0){return ; }if (queue->head < queue->tail){int i = queue->head;for (; i < queue->tail; i++){printf("%c ", queue->queue_data[i]);}}else{int i = queue->head;while (queue->head < queue->capacity){printf("%c", queue->queue_data[queue->head]);queue->head++;}queue->head = 0;for (i = queue->head; i < queue->tail; ++i){printf("%c ", queue->queue_data[i]);}}printf("\n");
}//通过两个队列实现一个栈的入栈，出栈和取栈顶元素操作
//栈的初始化函数
void StackInit(Stack* stack,int vector_capacity)
{if (stack == NULL){assert(0);return -1;}QueueInit(&stack->queue1,vector_capacity);QueueInit(&stack->queue2,vector_capacity);stack->size = 0;
}//销毁一个栈
void StackDestory(Stack* stack)
{if (stack == NULL){assert(0);return -1;}QueueDestory(&stack->queue1);QueueDestory(&stack->queue2);stack->size = 0;
}//入栈操作
void StackPush(Stack* stack,DataType2 value)
{if (stack == NULL){assert(0);return -1;}if (stack->queue1.size != 0) {QueuePush(&stack->queue1, value);}else {QueuePush(&stack->queue2, value);}stack->size++;
}void StackPop(Stack* stack)
{if (stack == NULL){assert(0);return -1;}if (stack->queue1.size == 0 && stack->queue2.size == 0){return ;}Queue* from = NULL;Queue* to = NULL;//判断数据放在了哪个队列if (stack->queue1.size != 0){from = &stack->queue1;to = &stack->queue2;}else{from = &stack->queue2;to = &stack->queue1;}while (from->size > 1){//取到from队列的队头元素DataType2 tmp = QueueGetTop(from);//from做一次出队列操作QueuePop(from);//将from的对头放到to队列QueuePush(to, tmp);}//把from队列剩的最后一个元素移出队列，模拟出栈QueuePop(from);//栈中的有效数据个数减一stack->size--;
}DataType2 StackGetTop(Stack* stack)
{if (stack == NULL){assert(0);return -1;}if ((stack->queue1.size == 0) && (stack->queue2.size == 0)){return ;}Queue* from = NULL;Queue* to = NULL;//判断数据放在了哪个队列if (stack->queue1.size != 0){from = &stack->queue1;to = &stack->queue2;}else{from = &stack->queue2;to = &stack->queue1;}while (from->size > 1){//取到from队列的队头元素DataType2 tmp = QueueGetTop(from);//from做一次出队列操作QueuePop(from);//将from的对头放到to队列QueuePush(to, tmp);}//读取from队列的最后一个元素，模拟读取栈顶DataType2 stacktop = QueueGetTop(from);QueuePop(from);QueuePush(to, stacktop);return stacktop;
}void PrintStack(Stack* stack)
{if (stack == NULL){assert(0);return -1;}if (stack->size == 0){return ;}Queue* print = NULL;if (stack->queue1.size == 0){print = &stack->queue2;}else{print = &stack->queue1;}PrintQueue(print);
}int main()
{Stack stack;//初始化StackInit(&stack,10);//入栈函数测试StackPush(&stack, 'a');StackPush(&stack, 'b');StackPush(&stack, 'c');StackPush(&stack, 'd');StackPop(&stack);PrintStack(&stack);DataType2 top_value = StackGetTop(&stack);printf("%c \n", top_value);StackDestory(&stack);system("pause");return 0;
}