Pairwise inversion of singly linked lists
Reverse : 1 2 3 4 5 into: 2 1 4 3 5
#include <iostream>
#include<stack>
#include<assert.h>
using namespace std;
typedef struct node
{
int data;
node *next;
}node;
/*增加*/
node * add(int n, node * head)
{
node * t = new node;
t->data = n;
t->next = NULL;
if (head == NULL)
{
head = t;
}
else if (head->next == NULL)
{
head->next = t;
}
else
{
node * p = head->next;
while (p->next != NULL)
{
p = p->next;
}
p->next = t;
}
return head;
}
/*输出链表数值*/
void print(node * head)
{
node * p = head;
while (p != NULL)
{
cout << p->data << " ";
p = p->next;
}
cout << endl;
}
node *reverse(node *head)
{
if(head==NULL||head->next==NULL)
{
return head;
}
node *p1=head;/*当前节点*/
node *p2=head->next;/*下个节点*/
node *temp;/*下个节点*/
node *previous=NULL;/* */
node * newHead = p2 == NULL ? p1 : p2;
while(p2!=NULL)
{
temp=p2->next;
p2->next=p1;
p1->next=temp;
if(previous!=NULL)
{
previous->next=p2;
}
if(temp==NULL)
{
break;
}
previous=p1;
p1=temp;
p2=temp->next;
}
return newHead;
}
int main()
{
node *head=NULL;
for(int i=1;i<10;i++)
{
head=add(i,head);
}
print(head);
head=reverse(head);
print(head);
cout << "Hello World!" << endl;
}
