Remove Duplicates in a Un-sorted Linked List..cpp

//Remove Duplicates in a Un-sorted Linked List.
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ft first
#define sc second
#define pb push_back
#define ins insert
#define all(v) v.begin(), v.end()
#define Sort(v) sort(all(v))
#define s(a, n) sort(a, a + n)
#define f1(i,a,b) for(ll i=a;i<b;i++)
#define f2(i,a,b,c) for(ll i=a;i<b;i+=c)
#define f3(i,a,b) for(ll i=a;i>=b;i--)
#define f4(i,a,b,c) for(ll i=a;i>=b;i-=c)
#define jatin(t) int t; cin >> t; while(t--)
const int N = 1e5+2, MOD = 1e9+7;
//int array[N];
//cout << (condition ? "YES\n" : "NO\n");
    Node * removeDuplicates( Node *head) 
    {
     // your code goes here
     Node *newhead=NULL,*tail=NULL;
     vector<int> vis(N,0);
     Node *newnode=new Node(head->data);
     newhead=newnode;
     tail=newnode;
     vis[head->data]=1;
     head=head->next;
     while(head!=NULL)
     {
         if(vis[head->data]==0)
         {
             Node* newnode=new Node(head->data);
             tail->next=newnode;
             tail=tail->next;
             vis[head->data]=1;
         }
         head=head->next;
     }
     return newhead;
    }