浙大数据结构02-线性结构1 两个有序链表序列的合并

L1和L2是给定的带头结点的单链表，其结点存储的数据是递增有序的；函数Merge要将L1和L2合并为一个非递减的整数序列。应直接使用原序列中的结点，返回归并后的带头结点的链表头指针。
输入样例：
3
1 3 5
5
2 4 6 8 10

输出样例：
1 2 3 4 5 6 8 10
NULL
NULL

#include <iostream>
#include <cstdlib>
using namespace std;
typedef int ElementType;
typedef struct Node *PtrToNode;
struct Node
{
    ElementType Data;
    PtrToNode Next;
};
typedef PtrToNode List;
List Read();/*读取数据*/
void Print(List L);/*输出链表*/
List Merge(List L1,List L2);/*合并链表*/
int main()
{
    List L1,L2,L;
    L1 = Read();
    L2 = Read();
    L = Merge(L1,L2);
    Print(L);
    Print(L1);
    Print(L2);
    return 0;
}
List Read()
{
    List L,LL,p;
    L = (List)malloc(sizeof(struct Node));
    L->Next = NULL;
    p = L;
    int n,m;
    cin >> n;
    while(n--)
    {
        cin >> m;
        LL = (List)malloc(sizeof(struct Node));
        LL->Data = m;
        LL->Next = NULL;
        p->Next = LL;
        p = LL;
    }
    return L;
}
List Merge(List L1,List L2)
{
    List L/*头结点*/,rear/*尾指针*/;
    L = (List)malloc(sizeof(struct Node));
    L->Next = NULL;
    rear = L;
    List p1 = L1->Next;
    List p2 = L2->Next;
    while(p1 && p2)
    {/*实现有序插入元素到L链表中*/
        if(p1->Data <= p2->Data)/*L1 <= L2*/
        {
            rear->Next = p1;
            rear = p1;
            p1 = p1->Next;
        }
        else/*L1 > L2*/
        {
            rear->Next = p2;
            rear = p2;
            p2 = p2->Next;
        }
    }
    rear->Next = p1?p1:p2;/*将剩余部分插入链表尾部*/
    L1->Next = NULL;
    L2->Next = NULL;
    return L;
}
void Print(List L)
{
    int flag = 0;/*控制输出空格*/
    if(L->Next == NULL)
    {
        cout << "NULL" << endl;
    }
    else
    {
        while(L->Next)
        {
            if(flag)
            {
                cout << " ";
            }
            else
            {
                flag = 1;
            }
            L = L->Next;
            cout << L->Data;
        }
        cout << endl;
    }
}