repeat

#include <stdio.h>
#include <stdlib.h>
int a[10000]= {0};
struct node
{
    int data;
    struct node *next;
};
int main()
{
    struct node *prev,*head,*p;
    int n,i;
    scanf("%d",&n);
    head=NULL;
    for(i=0; i<n; i++)
    {
        p=(struct node*)malloc(sizeof(struct node));
        scanf("%d",&p->data);
        p->next=NULL;
        if(head==NULL)
        {
            head=p;
        }
        else
        {
            prev->next=p;
        }
        prev=p;
    }
    struct node* ptr;
    ptr=head;
    while(ptr!=NULL)
    {
        a[ptr->data]++;
        ptr=ptr->next;
    }
    for(int j=0; j<n; ++j)
    {
        if(a[j]!=0)
        {
            printf("%d ",j);
        }
    }
    return 0;
}