Decimal Equivalent of Binary Linked List

PROBLEM :

Given a singly linked list of 0s and 1s find its decimal equivalent

   Input  : 0->0->0->1->1->0->0->1->0
   Output : 50
 
Decimal Value of an empty linked list is considered as 0.

Since the answer can be very large, answer modulo 1000000007 should be printed.

Input:
The task is to complete the method which takes one argument: the head of the linked list. The struct Node has a data part which stores the data and a next pointer which points to the next element of the linked list.
There are multiple test cases. For each test case, this method will be called individually.

Output:
The function should return should decimal equivalent modulo 1000000007

Constraints:
1 <=T<= 200
0 <=N<= 100
Data of Node is either 0 or 1

Example:
Input:
2
3
0 1 1  
4
1 1 1 0

Output:
3
14

--------------------------------------------------------------------------------
SIMPLE c++ IMPLEMENTATION :(Using Auxilary arry)
--------------------------------------------------------------------------------

/* Below global variable is declared in code for modulo arithmetic
const long long unsigned int MOD = 1000000007; */

/* Link list Node/
struct Node
{
    bool data;   // NOTE data is bool
    struct Node* next;
}; */

// Should return decimal equivalent modulo 1000000007 of binary linked list

long long unsigned int decimalValue(struct Node *head)
{
   if(head==NULL)
    return 0 ;
   
    long long unsigned int ans ;
    ans=0 ;
   
    while(head!=NULL)
    {
        ans=(ans*2) +(head->data) ;
        head=head->next ;
        ans=ans%MOD ;
    }
    return ans ;
}

---------------------------------------------------------------------------------

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