function removeDuplicates(llist) {
    let numSet=new Set()
    let current=llist;
    let prev=null;
    
    while(current){
        if(!numSet.has(current.data)){
           numSet.add(current.data)
        }
        else{
            prev.next=current.next;
            current=current.next;
            continue;
        }
        prev=current;
        current=current.next;
    }
    return llist;
}