单项链表出现段错误，找不到哪错了

问题遇到的现象和发生背景

问题相关代码，请勿粘贴截图

运行结果及报错内容 发生段错误

我的解答思路和尝试过的方法

我想要达到的结果

这个简单程序是用来实现链表的插入、删除、查找等基本操作

```c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct LNode{
    int date;
    struct LNode *next;
}Node; 
#define len sizeof(Node) 
Node* creat(int n);
void output(Node*begin);
void get(Node *begin,int n);
Node* insert(Node*begin,int n,int x);
Node* delet(Node*begin,int n);
int main()
{
    int n,ret,x,i;
    char ch[4][20] = {{"show"}, {"delete"}, {"insert"},{"get"}};
    char str[20];
    scanf("%d",&n);
    Node *begin;
    begin = creat(n);
    int count;
    scanf("%d",&count);
    while(count)
    {
        scanf("%s",str); 
        for(i = 0;i < 4;i++)
            if(strcmp(ch[i],str)==0)
                break;
        switch(i)
        {
            case 0:output(begin);break;
            case 1:scanf("%d",&n);begin = delet(begin,n);break;
            case 2:scanf("%d%d",&n,&x);begin = insert(begin,n,x);break;
            case 3:scanf("%d",&n);get(begin,n);break;
        }
        count--;
    }
    return 0;
}
Node* creat(int n)
{
    int count = 0;
    Node *p1,*p2;
    p2 = malloc(len);
    p2->next = NULL;
    while(n)
    {
        p1 = malloc(len);
        scanf("%d",&p1->date);
        p1->next = p2->next;
        p2->next = p1;
        n--;
    }
    return p1;
}
void output(Node*begin)
{
    Node *p1 = begin;
    int flag = 0;
    while(p1)
    {
        printf("%d ",p1->date);
        p1 = p1->next;
        flag = 1;
    }
    if(flag==0)
        printf("Link list is empty\n");
    else
        putchar('\n');
}
void get(Node *begin,int n)
{
    Node *p1;
    p1 = begin;
    int i = 0;
    while(i < n-1 && p1)
    {
        p1 = p1->next;
        i++;
    }
    if(i > n || p1==NULL)
        printf("get fail\n");
    if(p1->next)
        printf("%d\n",p1->date);
}
Node* insert(Node*begin,int n,int x)
{
    Node *front,*head,*move,*temp;
    head = move = begin;
    int i = 0;
    while(i<n-1&&move)
    {
        front = move; move = move->next;
        i++;
    }
    if(move==NULL)
    {
        head=malloc(len);
        head->date=x; head->next=NULL;
    }
    if(move)
    {
        if(front==NULL)
        {
            head = temp = malloc(len);
            temp->date = x;
            temp->next = move;
        }
        else
        {
            temp = malloc(len);
            temp->date = x;
            front->next = temp; temp->next = move;
        }
    }
    return head;
    
}
Node* delet(Node*begin,int n)
{
    Node *front = NULL,*move = begin,*head = begin;
    int i=0,flag = 0;
    move = begin;
    while(i<n-1 && move)
    {
        front = move;
        move = move->next;
        i++;
    }
    if(move==head&&move)
    {
        head = head->next;
        flag=1;
    }
    else if(move)
    {
        front->next = move->next;
        flag=1;
    }    
    if(flag)
        printf("delete OK\n");
    else
        printf("delete fail\n");
    return head; 
}

```

TL;DR

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