C++链表冒泡，归并，插入排序（纯指针）

#include <iostream>
using namespace std;
//别问我为什么要写链表的冒泡排序。
struct Node
{
    int data;
    Node *next;
    Node(int d = int()) :data(d), next(NULL){}
};
class List
{
public:
    List(int a[], int n)
    {
        first = NULL;
        for (int i = 0; i < n; i++)
        {
            if (first == NULL)
            {
                first = new Node(a[i]);
            }
            else
            {
                Node *s = new Node(a[i]);
                Node *p = first;
                while (p->next != NULL)
                {
                    p = p->next;
                }
                s->next = p->next;
                p->next = s;
            }
        }
    }
    //////////////////////////////////////////////////////////////////////////////
    //冒泡排序
    void Bul()
    {
        Node *ptr_one = first;
        Node *ptr_twe;
        Node *pr_one = NULL;
        Node *save = NULL;
        if (ptr_one == NULL || ptr_one->next == NULL)return;
        while (ptr_one != NULL && ptr_one->next != NULL)
        {
            Node *pr_twe = ptr_one;
            Node *m2 = NULL;
            save = ptr_one;
            for (ptr_twe = ptr_one->next; ptr_twe != NULL;)
            {

                if (ptr_one->data > ptr_twe->data)
                {
                    if (pr_one == NULL)
                    {
                        Node *m1;
                        Node *a;
                        m1 = ptr_twe->next;
                        m2 = ptr_one->next;

                        first->next = m1;
                        pr_twe->next = first;
                        a = first;
                        ptr_twe->next = m2;
                        first = ptr_twe;

                        save = ptr_twe;

                        ptr_twe = a;
                        ptr_one = first;
                    }
                    else
                    {
                        Swap(pr_one, pr_twe);
                        save = pr_one->next;
                        ptr_one = save;
                        ptr_twe = pr_twe->next;
                    }
                }
                pr_twe = ptr_twe;
                if (ptr_twe == NULL)continue;
                ptr_twe = ptr_twe->next;
            }
            pr_one = save;

            ptr_one = pr_one->next;
        }
    }
    void Swap(Node *prv1, Node *&prv2)
    {
        if (prv1->next == prv2)
        {
            Node *m = prv1->next;
            Node *n = prv2->next;
            m->next = n->next;
            n->next = m;
            prv1->next = n;
            prv2 = n;
        }
        else
        {
            Node *m1 = prv1->next;
            Node *save = m1->next;
            Node *m2 = prv2->next;
            m1->next = m2->next;
            prv2->next = m1;
            m2->next = save;
            prv1->next = m2;
        }
    }

    void Printf()
    {
        Node *p = first;
        while (p != NULL)
        {
            cout << p->data << "   ";
            p = p->next;
        }
        cout << endl;
    }
    //////////////////////////////////////////////////////////////////////////////////////
    //2路归并排序。
    Node *GetMidNode(Node* Start_Ptr)
    {
        Node *slow = Start_Ptr;
        Node *fast = Start_Ptr;
        if (Start_Ptr == NULL || Start_Ptr->next == NULL || Start_Ptr->next->next==NULL)return Start_Ptr;
        while (fast != NULL)
        {
            if (fast->next == NULL)
            {
                break;
            }
            fast = fast->next->next;
            slow = slow->next;
        }
        return slow;
    }
    void Merge()
    {
        Merge(first);
    }
    Node* Merge(Node *Start_Ptr)
    {
        if (Start_Ptr==NULL || Start_Ptr->next == NULL) return Start_Ptr;
        else
        {
            Node *Mid_Ptr = GetMidNode(Start_Ptr);
            Node *Next_Ptr = Mid_Ptr->next;
            Mid_Ptr->next = NULL;
            return Merage(Merge(Start_Ptr),Merge(Next_Ptr));
        }
    }
    Node* Merage(Node *ptr1, Node *ptr2)
    {
        Node* p1 = ptr1;
        Node *p2 = ptr2;
        Node *p = new Node();
        Node *save = p;
        while (p1 != NULL && p2 != NULL)
        {
            if (p1->data > p2->data)
            {
                p->next=p2;
                p = p2;
                p2 = p2->next;
            }
            else
            {
                p->next = p1;
                p = p1;
                p1 = p1->next;
            }
        }   
        if (p1 == NULL)
        {
            p->next = p2;
        }
        if (p2 == NULL)
        {
            p->next = p1;
        }
        first = save->next;
        delete save;
        save = NULL;
        return first;
    }
    //////////////////////////////////////////////////////////////////////////////////////////
    //插入排序。
    void Insert()
    {
        Node *ptr_first = first;
        Node *pr_first;
        Node *ptr_twe;
        Node *pr_twe;
        Node *save;
            for (; ptr_first != NULL;pr_first = ptr_first)
            {
                save = ptr_first->next;
                if (ptr_first == first)
                {
                    ptr_twe = ptr_first;
                    ptr_twe->next = NULL;
                    first = ptr_twe;
                }
                else
                {
                    Node *p = ptr_twe;

                    Node *q = ptr_first;
                    while (p!=NULL&&p->data<q->data)
                    {
                        pr_twe = p;
                        p = p->next;
                    }
                    if (p == first)
                    {
                        //假设是第一个节点插入。
                        q->next = p;
                        ptr_twe = q;
                        first = ptr_twe;

                    }
                    else if(p == NULL)
                    {
                        pr_twe->next = q;
                        q->next = NULL;
                    }
                    else
                    {
                        q->next = pr_twe->next;
                        pr_twe->next = q;
                    }
                }
                ptr_first = save;
            }
    }
private:
    Node *first;
};
int main()
{
    int a[] = { 6,7,2,1,0,7,5,23,4,5,423,4,100,-32,4,-3,1};
    List list(a, sizeof(a) / sizeof(int));
    //list.Merge();
    //list.Bul();
    list.Insert();
    list.Printf();
    return 0;
}