Find a node in LL.cpp

/*
Find a node in LL (recursive)
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Given a linked list and an integer n you need to find and return index where n is present in the LL. Do this recursively.
Return -1 if n is not present in the LL.
Indexing of nodes starts from 0.
Input format :
Line 1 : Linked list elements (separated by space and terminated by -1)
Line 2 : Integer n 
Output format :
Index
Sample Input 1 :
3 4 5 2 6 1 9 -1
5
Sample Output 1 :
2
Sample Input 2 :
3 4 5 2 6 1 9 -1
6
Sample Output 2 :
4
*/


/**********
 * Following is the Node class that is already written.
 
class Node{
public:
    int data;
    Node *next;
    Node(int data){
        this -> data = data;
        this -> next = NULL;
    }
};
 
*********/

int helper(Node *head, int n, int index){
     
    if(head==NULL){
        return -1;
    }
    
    
    if(head->data==n){
        return index;
    }
    int smallAns=helper(head->next, n, index+1);
    return smallAns;
    
    
}


int indexOfNRecursive(Node *head, int n) {
    /* Don't write main().
     * Don't read input, it is passed as function argument.
     * Return output and don't print it.
     * Taking input is handled automatically.
     */
    
    int y=helper(head, n, 0);
    return y;
   
    
}