两个差不多的代码，一个正常运行，一个链表会报错。到底是为什么？

Question

#include<stdio.h>                             
#include<stdlib.h>

typedef int ElemType;
typedef struct LNode {
 ElemType Data;
 struct LNode * Next;
}LNode, *List;

List CreateList() {
 List head, L, pro;
 int n;
 L = (List)malloc(sizeof(struct LNode));
 head = L;
 scanf("%d", &n);
 if (n == -1) 
 {
  L = NULL;
  return L;
 }
 while (1)
 {
  if (n == -1)
  { //序列结束符号
   pro->Next = NULL; //序列尾指向NULL
   free(L); //释放多余节点
   return head;
  }
  L->Data = n;
  L->Next = (List)malloc(sizeof(LNode));
  pro = L;
  L = L->Next;
  scanf("%d", &n);
 }
}

List CombineList(List L1, List L2)
{
 List L, head;
 L = (List)malloc(sizeof(LNode));
 head = L;// 建立新节点
 while (L1&&L2)
 {
  // 进行挨个比较
  if (L1->Data <= L2->Data)
  {
   L->Next = L1;
   L = L->Next;
   L1 = L1->Next;
  }
  else
  {
   L->Next = L2;
   L = L->Next; 
   L2 = L2->Next;
  }
 }
 if (L1) // L2进行到空或者L2初始为空
 {

  L->Next = L1;
  L = head;
  head = head->Next;
  free(L);
  return head;
 }
 else if (L2)  // L1进行到空或者L1初始为空
 {
  L->Next = L2;
  L = head;
  head = head->Next;
  free(L);
  return head;
 }
 else                //两者初始皆为空
  return  NULL;
}


int main() {
 List L, L1, L2;
 int m, n, i;
 L1 = CreateList();
 L2 = CreateList();
 L = CombineList(L1, L2);
 if (!L)
  printf("NULL");            //链表为空时输出NULL
 else
 {
  while (L->Next)
  {
   printf("%d ", L->Data);
   L = L->Next;
  }
  printf("%d", L->Data);
 }
 return 0;
}

#include<stdio.h>                             
#include<stdlib.h>
#include<iostream>
using namespace std;
typedef struct Node{
    int data;
    struct node *next;
}LinkList,*List; 
List CreatList(){
    List head,l,node;
    int n;
    l=(List)malloc(sizeof(struct Node));
    head=l;
    cin>>n;
    if(n==-1){
        l=NULL;
        return head;
    }
    else{
        if(n==-1){
            node->next=NULL;
            free(l);
            return head;
        }
        l->next=(List)malloc(sizeof(struct Node));
        l->data=n;
        node=l;
        l=l->next;
        cin>>n;
    }
}
List CombineList(List L1,List L2){
    List head,l;
    l=(List)malloc(sizeof(struct Node));
    head=l;
    while(L1&&L2){
        if(L1->data<=L2->data){
            l->next=L1;
            l=l->next;
            L1=L1->next;
        }
        else{
            l->next=L2;
            l=l->next;
            L2=L2->next;
        }
    }
    else{
        if(L1)//L2为空 
        {
            l->next=L1;
            l=head;
            head=head->next;
            free(l);
        }
        if(L2)
        {
            l->next=L2;
            l=head;
            head=head->next;
            free(l);
        }
        else{
            return NULL;
        }
    }
}
int main(){
    List L,L1,L2;
    int m,n,i;
    L1=CreatList();
    L2=CreatList();
    L=CombineList(L1,L2);
    if (!L)
      printf("NULL");            
     else
     {
      while (L->Next)
      {
       printf("%d ", L->Data);
       L = L->Next;
      }
      printf("%d", L->Data);
     }
    
}

Answer 1

没人吗？