链表逆序

思路：3个辅助指针,不断移动指针位置

#include <iostream>
using namespace std;
typedef struct Node
{
    int val;
    struct Node* next;
}node;
node* reverse(node* head)
{
    node* p=NULL;
    node* q=NULL;
    node* r=NULL;
    p=head;
    q=head->next;
    head->next=NULL;
    while(q!=NULL)
    {
        r=q->next;
        q->next=p;
        p=q;
        q=r;
    }
    return p;
}
int main()
{
    node* n1=new node;
    node* n2=new node;
    node* n3=new node;
    n1->val=1;
    n2->val=2;
    n3->val=3;
    n1->next=n2;
    n2->next=n3;
    n3->next=NULL;
    node* h=new node;
    h=reverse(n1);
    while(h!=NULL)
    {
        cout<<h->val<<" ";
        h=h->next;
    }
}