逆序单链表

#include <iostream>
using namespace std;

struct Node
{
    Node *next;
    int elem;
};

void creatList(Node* &head)
{
    head = new Node;
    int elem;
    cin>>elem;
    head->elem = elem;
    Node *p = head;
    while(cin>>elem&&elem)
    {
        Node *q = new Node;
        q->elem = elem;
        p->next = q;
        p = p->next;
    }
    p->next = NULL;
}
void printList(Node* &head)
{
    cout<<head->elem<<" ";
    Node *p = head->next;
    while(p)
    {
        cout<<p->elem<<" ";
        p = p->next;
    }
    cout<<endl;
}
void removeX(Node* &head,int x)
{
    Node *p;
    if(head == NULL)
        return;
    else if(head->elem == x)
    {
        p = head;
        head = head->next;
        free(p);
        removeX(head, x);
    }
    else
        removeX(head->next, x);
}

Node* getElem(Node* head,int i)
{
    int j = 1;
    Node *p = head;
    if(head==NULL)
        return head;
    while(p&&j<i)
    {
        j++;
        p = p->next;
    }
    return p;
}
void insertNode(Node* &head,int i,int data)
{
    Node* p = getElem(head, i-1);
    Node* q = new Node;
    q->elem = data;
    q ->next = p ->next;
    p ->next = q;
}
void deleteNode(Node* &head,int i)
{
    Node* p = getElem(head, i-1);
    Node* q = p->next;
    p->next = q->next;
    free(q);
}
void reverseList(Node* &head)
{
    if(head == NULL||head ->next == NULL)
        return ;
    Node *pre = head;
    Node *cur = head->next;
    Node *nex = NULL;
    while(cur)
    {
        nex = cur -> next;
        cur ->next = pre;
        pre = cur;
        cur = nex;
    }
    head->next = NULL;
    head = pre;
}
int main()
{
    Node *p;
    creatList(p);
    printList(p);
    //removeX(p, 4);
    insertNode(p, 2, 100);
    printList(p);
    cout<<getElem(p, 3)->elem<<endl;
    deleteNode(p, 2);
    printList(p);
    reverseList(p);
    printList(p);
    return 0;
}