思路分析

代码实现：

typedef int STDataType;
typedef struct Stack
{int* a;int top;//下标int capacity;
}ST;
//栈的初始化
void STInit(ST* ps);
//栈的插入
void STPush(ST* ps, STDataType x);
//栈的删除
void STPop(ST* ps);
//
int STSize(ST* ps);
//判断栈是否为空
bool STEmpty(ST* ps);
//栈的销毁
void STDestroy(ST* ps);
//访问栈顶元素
STDataType STTop(ST* ps);
//栈的初始化
void STInit(ST* ps)
{assert(ps);ps->a = malloc(sizeof(STDataType) * 4);if (ps->a == NULL){perror("malloc fail");return;}ps->capacity = 4;ps->top = 0;//代表top表示的是栈顶元素的下一个位置：刚开始top指向的是第一个元素，表示0，当第一个元素插入后top++表示1
}
//栈的插入
void STPush(ST* ps, STDataType x)
{assert(ps);if (ps->top == ps->capacity){STDataType* tmp = (STDataType*)realloc(ps->a, sizeof(STDataType) *  ps->capacity * 2);//扩容到当前的二倍if (tmp == NULL){perror("realloc fail");return;}ps->a = tmp;ps->capacity *= 2;}ps->a[ps->top] = x;ps->top++;
}
//栈的删除
void STPop(ST* ps)
{assert(ps);assert(!STEmpty(ps));ps->top--;/*在栈操作函数中，栈指针 ps 是操作栈的基础，如果 ps 为 NULL，那么后续对 ps 指向的栈结构的任何访问（如 ps->top）都会导致未定义行为，通常是程序崩溃。因此，在进行栈操作之前，需要先确保 ps 不是 NULLassert(!STEmpty(ps)); 实际上是在检查栈不为空的情况下才继续执行后续操作*/
}
//
int STSize(ST* ps)
{assert(ps);return ps->top;
}
//判断栈是否为空
bool STEmpty(ST* ps)
{assert(ps);return ps->top == 0;
}
//栈的销毁
void STDestroy(ST* ps)
{assert(ps);free(ps->a);ps->a = NULL;ps->top = 0;ps->capacity = 0;
}
//访问栈顶元素
STDataType STTop(ST* ps)
{assert(ps);assert(!STEmpty(ps));return ps->a[ps->top-1];
}typedef struct {ST pushst;ST popst;} MyQueue;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 myQueuePop(MyQueue* obj) {//导数据if(STEmpty(&obj->popst)){while(!STEmpty(&obj->pushst)){STPush(&obj->popst,STTop(&obj->pushst));//将栈顶元素导入STPop(&obj->pushst);//删除栈顶元素}}int front=STTop(&obj->popst);STPop(&obj->popst);return front;
}int myQueuePeek(MyQueue* obj) {//导数据if(STEmpty(&obj->popst)){while(!STEmpty(&obj->pushst)){STPush(&obj->popst,STTop(&obj->pushst));//将栈顶元素导入STPop(&obj->pushst);//删除栈顶元素}}int front=STTop(&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);
}