数据结构4——栈

1. 栈的概念及结构

栈的概念：

栈是一种特殊的线性表，其只允许在固定的一端进行插入和删除元素操作。进行数据插入和删除操作的一端称为栈顶，另一端称为栈底。栈中的数据元素遵守后进先出LIFO（Last In First Out）的原则。

压栈：栈的插入操作叫做进栈/压栈/入栈，入数据在栈顶。

出栈：栈的删除操作叫做出栈。出数据也在栈顶。

图解：

 

2. 栈的实现

1. 初始化栈

//初始化
void STInit(ST* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
}

2. 销毁栈

//销毁
void STDestroy(ST* ps)
{
	assert(ps);

	free(ps->a);
	ps->a = NULL;
	ps->top = ps->capacity = 0;
}

3. 入栈

//入栈
void STPush(ST* ps, STDateType x)
{
	assert(ps);
	
	if (ps->top == ps->capacity)
	{
		int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDateType* tmp = (STDateType*)realloc(ps->a, sizeof(STDateType) * newCapacity);
		if (tmp == NULL)
		{
			perror("realloc fail");
			exit(-1);
		}

		ps->a = tmp;
		ps->capacity = newCapacity;
	}

	ps->a[ps->top] = x;
	ps->top++;
}

4. 出栈

//出栈
void STPop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);//防止栈为空

	--ps->top;
}

5.获取栈顶元素

//获取栈顶元素
STDateType STTop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);

	return ps->a[ps->top - 1];
}

6. 容量

//容量
int STSize(ST* ps)
{
	assert(ps);

	return ps->top;
}

7. 判空

//判空
bool STEmpty(ST* ps)
{
	assert(ps);

	return ps->top == 0;
}

3. 测试

int main()
{
	ST st;
	STInit(&st);
	STPush(&st, 1);
	STPush(&st, 2);
	STPush(&st, 3);
	STPush(&st, 4);
	STPush(&st, 5);

	//遍历栈，需要边获取边删除
	while (!STEmpty(&st))
	{
		printf("%d ", STTop(&st));
		STPop(&st);
	}
	printf("\n");

	STDestroy(&st);
	return 0;
}

 

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源代码 

Stack.h

#pragma once

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <stdbool.h>


typedef int STDateType;
typedef struct Stack
{
	STDateType* a;
	int top;
	int capacity;
}ST;

void STInit(ST* ps);//初始化函数声明
void STDestroy(ST* ps);//销毁函数声明
void STPush(ST* ps, STDateType x);//入栈函数声明
void STPop(ST* ps);//出栈函数声明
STDateType STTop(ST* ps);//获取栈顶元素
int STSize(ST* ps);//容量
bool STEmpty(ST* ps);//判空

Stack.c

#define _CRT_SECURE_NO_WARNINGS 1

#include "Stack.h"

//初始化
void STInit(ST* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
}

//销毁
void STDestroy(ST* ps)
{
	assert(ps);

	free(ps->a);
	ps->a = NULL;
	ps->top = ps->capacity = 0;
}

//入栈
void STPush(ST* ps, STDateType x)
{
	assert(ps);
	
	if (ps->top == ps->capacity)
	{
		int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDateType* tmp = (STDateType*)realloc(ps->a, sizeof(STDateType) * newCapacity);
		if (tmp == NULL)
		{
			perror("realloc fail");
			exit(-1);
		}

		ps->a = tmp;
		ps->capacity = newCapacity;
	}

	ps->a[ps->top] = x;
	ps->top++;
}

//出栈
void STPop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);//防止栈为空

	--ps->top;
}

//获取栈顶元素
STDateType STTop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);

	return ps->a[ps->top - 1];
}


//容量
int STSize(ST* ps)
{
	assert(ps);

	return ps->top;
}

//判空
bool STEmpty(ST* ps)
{
	assert(ps);

	return ps->top == 0;
}

test.c

#define _CRT_SECURE_NO_WARNINGS 1

#include "Stack.h"

int main()
{
	ST st;
	STInit(&st);
	STPush(&st, 1);
	STPush(&st, 2);
	STPush(&st, 3);
	STPush(&st, 4);
	STPush(&st, 5);

	//遍历栈，需要边获取边删除
	while (!STEmpty(&st))
	{
		printf("%d ", STTop(&st));
		STPop(&st);
	}
	printf("\n");

	STDestroy(&st);
	return 0;
}