[数据结构与算法]堆栈，链式（个人记录）

在计算机中有一个重要的概念——堆栈。堆栈是指这样一段内存，?它可以理解为一个?筒结构，?先放进筒中的数据被后放进筒中的数据“压住”，只有在后放进筒中的数据都取出后，?先放进去的数据才能被取出，这称为“后进先出”。堆栈的长度可以随意增加。堆栈结构可以?用链表实现。

#include <stdio.h>
#include <stdlib.h>
 
typedef struct stack stack;
 
struct stack{
    int data;
    stack *next;
};
 
stack *head,*pr;
//压入
void PushStack(int data)
{
    stack *p = (stack *)malloc(sizeof(stack));
    stack *q;
    if(head->next==NULL)
    {
        p->data = data;
        p->next = NULL;
        head->next = p;
    }
    else
    {
        q = head->next;
        p->next = q;
        p->data = data;
        head->next = p;
    }
}
//弹出
void PopStack()
{
    stack *p;
    if(head->next->next==NULL)
    {
        printf("no data\n");
    }
    else
    {
        p = head->next;
        head->next = p->next;
    }
    free(p);
}
//打印
void PrintStack()
{
    stack *p;
    p = head->next;
    printf("从栈顶向下遍历为：\n");
    while(p)
    {
        printf("%d ",p->data);
        p = p->next;
    }
    printf("\n");
}
 
int main() {
    int data,pushNum,popNum,i;
    char ch;
    head = (stack *)malloc(sizeof(stack));
    head->next = NULL;
    printf("请输入要压入堆栈的数的个数：");
    scanf("%d",&pushNum);
	printf("请输入数据：\n");
    for(i = 0;i < pushNum;i++)
    {
        scanf("%d",&data);
        PushStack(data);
    }
    PrintStack();
    flag:;
    printf("你是否要将数据弹出堆栈？(y/n)");
    getchar();
    scanf("%c",&ch);
    if(ch == 'n')
    {
        PrintStack();
    }
    else if(ch == 'y')
    {
        printf("你想弹出多少数据？");
        scanf("%d",&popNum);
        while(popNum > pushNum)
        {
			printf("错误的数量!\n");
			printf("你想弹出多少数据？");
			scanf("%d",&popNum);
		}
        while(popNum--)
        {
            PopStack();
        }
        PrintStack();
    }
    else
    {
		printf("错误的指令!\n");
		goto flag;
	}
	
	return 0;
}

另一个：

#include<stdio.h>
#include<stdlib.h>
struct stack
{
	int data;
	struct stack *next;
};

typedef struct stack stack;
stack *head,*pr;
int nodeNumber = 0;

stack *CreateNode(int data)
{
	stack *p;
	p = (stack *)malloc(sizeof(stack));
	if(p == NULL)
	{
		printf("No enough memory!\n");
		exit(0);
	}
	p->next = NULL;
	p->data = data;
	return p;
}

stack *Pushstack(int num)
{
	if(nodeNumber == 0)
	{
		head = CreateNode(num);
		pr = head;
		nodeNumber++;
	}
	else
	{
		pr->next = CreateNode(num);
		pr = pr->next;
		nodeNumber++;
	}
	return pr;
}

int Popstack(void)
{
	stack *p;
	int result;
	p = head;
	while(1)
	{
		if(p->next == NULL)
		{
			break;
		}
		else
		{
			pr = p;
			p = p->next;
			nodeNumber--;
		}
	}
	pr->next = NULL;
	result = p->data;
	free(p);
	return result;
}

int main()
{
	int pushNum;
	int popNum[5];
	int i,n;
	printf("How many Data do you want push?");
	scanf("%d",&n);
	for(i = 0;i < n;i++)
	{
		scanf("%d",&pushNum);
		Pushstack(pushNum);
		printf("Push %dth Data : %d\n",i+1,pushNum);
	}
	for(i = 0;i < n;i++)
	{
		popNum[i] = Popstack();
		printf("Pop %dth Data : %d\n",n-i,popNum[i]);
	}
	return 0;
}

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