单向链表每隔K个逆序输出

[qq_38190854]

输入一个单向链表，使这个链表每k个元素便逆序输出，下面是我用的程序，运行不出结果，问题应该是出在reverse函数上，请大神帮我看一下，非常感谢
#include<iostream>
#include<stdlib.h>
using namespace std;
struct node
{
int data;
node * next;

};
typedef node* nodeptr;
nodeptr reverse(nodeptr& head,int k)
{

nodeptr now=head;
int cnt=1;
nodeptr old,tmp;
old=now->next;
tmp=old->next;
while(cnt<k&&head&&old)
{
old->next=now;
now=old;
old=tmp;
tmp=old->next;
cnt++;
}
while(old)
head->next=reverse(old,k);

return now;
}
void push(nodeptr& head, int data)
{
if (head == NULL)
{
node* newnode = new node;
newnode->data = data;
newnode->next = NULL;
head = newnode;
}
else
{
node* newnode = new node;
newnode->data = data;
newnode->next = head;
head = newnode;
}
}
void print(nodeptr head)
{
while (head)
{
cout << head->data <<" ";
head = head->next;

}
}
/*void clear(nodeptr head)
{
while(head)
{delete head;
head=head->next;
}
}*/
int main()
{
using namespace std;
nodeptr head = NULL;
nodeptr end = NULL;
push(head, 8);
push(head, 7);
push(head, 6);

print(head);
end=reverse(head,2);
print(end);

system("pause");
return 0;
}

[自信男孩]

需求能更详细一些吗？每k个逆序输出。建议举个例子，怎么算是每隔k个逆序输出

[qq_38190854]

引用 1 楼 cfjtaishan 的回复:

需求能更详细一些吗？每k个逆序输出。建议举个例子，怎么算是每隔k个逆序输出

不好意思，没说清楚，比如链表是1-2-3-4-5-6-7-8，每三个逆序输出，则输出变成了3-2-1-6-5-4-8-7

[paschen]

old = now->next; 这句执行后，old可能为NULL，再执行后面的tmp = old->next;访问了NULL指针，导致程序崩溃

[MHY1249]

#include "stdafx.h"
#include <Windows.h>
#include <string>
using namespace std;

typedef struct linkNode{
	int nData;
	struct linkNode *pNext;
}LINKNODE,*PLINKNODE;


void showLink(LINKNODE *pHead){
	if(!pHead || !pHead->pNext){
		return ;
	}
	
	LINKNODE *pData = pHead->pNext;

	while(pData){
		printf("%d ",pData->nData);
		pData=pData->pNext;
	}
	
	printf("\n");
	return ;
}

void freeLink(LINKNODE * &pHead){
	if(!pHead || !pHead->pNext){
		return ;
	}

	LINKNODE *pData = pHead->pNext;
	while(pData){
		LINKNODE *pTemp = pData->pNext;
		free(pData);
		pData = pTemp;
	}

	pHead->pNext = NULL;
	
	return ;
}

// 后插法 
void createLink(int nNumber,LINKNODE * &pHead){
	if(!pHead){
		pHead = (PLINKNODE)malloc(sizeof(LINKNODE));
	}	

	LINKNODE *pData = pHead;

	while(nNumber-->0){
		LINKNODE *pTempNode = (PLINKNODE)malloc(sizeof(PLINKNODE));
		printf("请输入链表中的数值: \n");
		scanf("%d",&pTempNode->nData);
		pTempNode->pNext = NULL;
		pData->pNext = pTempNode;
		pData = pData->pNext;
	}

	showLink(pHead);
}

// 前插法
void addLinkByPreInsert(LINKNODE * &pHead,int nData){
	if(!pHead){
		return ;
	}
	
	LINKNODE *pData = (PLINKNODE)malloc(sizeof(LINKNODE));
	pData->nData = nData;
	if(!pHead->pNext){
		pHead->pNext= pData;
		pData->pNext = NULL;
	}else{
		LINKNODE *pTemp = pHead->pNext;
		pHead->pNext = pData;
		pData->pNext = pTemp;
	}
	
	return ;
}

void reverseLink(LINKNODE *pHead){
	if(!pHead || !pHead->pNext){
		return ;
	}

	printf("请输入k值: \n");
	int k = 0;
	scanf("%d",&k);
	
	LINKNODE *pNewLink = (PLINKNODE)malloc(sizeof(LINKNODE));
	pNewLink->pNext = NULL;
	
	int i = 0;
	LINKNODE *pData = pHead->pNext;
	while(pData){
		if(i == k){
			showLink(pNewLink);
			freeLink(pNewLink);
			i = 0;
		}

		addLinkByPreInsert(pNewLink,pData->nData);
		pData=pData->pNext;
		i++;
	}

	if(pNewLink->pNext){
		showLink(pNewLink);
	}
	
	return ;
}



int _tmain(int argc, _TCHAR* argv[])
{
	
	LINKNODE *pHead  = NULL;
    createLink(10,pHead);
	reverseLink(pHead);

	return 0;
}

可以参考一下

[赵4老师]

数据结构对单链表进行数据排序 http://bbs.csdn.net/topics/392201633