前言：本节博客分享了用栈实现队列效果的思路以及代码，有需要借鉴即可。

1.题目及链接

LINK

2.思路分析

如果要用栈实现队列，我们直到栈是先入后出的一个效果，所以我们可以用两个栈，这样逆转两次数不就是入栈之前数组的顺序嘛。下面是一些图辅助理解：

3.代码示例

#include<stdio.h>
#include<assert.h>
#include<stdlib.h>
#include<stdbool.h>//用数组的方式实现栈结构
typedef int STDateType;
typedef struct Stack
{STDateType* arr;int top;int capacity;
}ST;//初始化与销毁
void StackInit(ST* ps);
void StackDestroy(ST* ps);//入栈出栈
void StackPush(ST* ps,STDateType x);
STDateType StackTop(ST* ps);
void StackPop(ST* ps);//统计与判断
bool StackEmpty(ST* ps);
int StackSize(ST* ps);void StackInit(ST* ps)
{assert(ps);ps->arr = NULL;ps->capacity = ps->top = 0;
}void StackDestroy(ST* ps)
{assert(ps);free(ps->arr);ps->arr = NULL;ps->capacity = ps->top = 0;ps = NULL;
}void StackPush(ST* ps, STDateType x)
{assert(ps);if (ps->capacity == ps->top){//初始值的情况int newcapacity = ps->capacity == 0 ? 4 : 2 * ps->capacity;STDateType* temp = (STDateType*)realloc(ps->arr, newcapacity * sizeof(STDateType));if (temp == NULL){perror("malloc fail!");exit(-1);}ps->arr = temp;ps->capacity = newcapacity;}ps->arr[ps->top++] = x;
}void StackPop(ST* ps)
{assert(ps);assert(ps->top > 0);ps->top--;
}STDateType StackTop(ST* ps)
{assert(ps);return ps->arr[ps->top - 1];
}bool StackEmpty(ST* ps)
{assert(ps);return ps->top == 0;
}int StackSize(ST* ps)
{assert(ps);return ps->top;
}typedef struct {ST pushtack;ST poptack;
} MyQueue;MyQueue* myQueueCreate() {//首先要创建一个队列结构体MyQueue* obj = (MyQueue*)malloc(sizeof(MyQueue));//对队列结构体中的栈做初始化调整StackInit(&obj->pushtack);StackInit(&obj->poptack);//返回return obj;
}//将元素 x 推到队列的末尾
void myQueuePush(MyQueue* obj, int x) {//插入数据StackPush(&obj->pushtack,x);
}//返回队列开头的元素
int myQueuePeek(MyQueue* obj) {//分两种情况:1.poptack为空2.poptack不为空if(StackEmpty(&obj->poptack))//为空需要导数据{while(!StackEmpty(&obj->pushtack)){int top = StackTop(&obj->pushtack);//取出push数据StackPop(&obj->pushtack);//删除pop数据StackPush(&obj->poptack,top);//放入push}}//poptack不为空return StackTop(&obj->poptack);
}//从队列的开头移除并返回元素
int myQueuePop(MyQueue* obj) {int front = myQueuePeek(obj);//取出StackPop(&obj->poptack);//删除return front;//返回
}//如果队列为空，返回 true ；否则，返回 false
bool myQueueEmpty(MyQueue* obj) {//两个都为空return StackEmpty(&obj->pushtack)&&StackEmpty(&obj->poptack);
}//释放
void myQueueFree(MyQueue* obj) {StackDestroy(&obj->pushtack);StackDestroy(&obj->poptack);free(obj);
}/*** Your MyQueue struct will be instantiated and called as such:* MyQueue* obj = myQueueCreate();* myQueuePush(obj, x);* int param_2 = myQueuePop(obj);* int param_3 = myQueuePeek(obj);* bool param_4 = myQueueEmpty(obj);* myQueueFree(obj);
*/

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完。