Convert Binary Number in a Linked List to Integer

1290. Convert Binary Number in a Linked List to Integer

Given head which is a reference node to a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary representation of a number.
Return the decimal value of the number in the linked list.
The most significant bit is at the head of the linked list.
Example 1:

Input: head = [1,0,1]
Output: 5
Explanation: (101) in base 2 = (5) in base 10
Example 2:

Input: head = [0]
Output: 0

class Solution {
    public int getDecimalValue(ListNode head) {
        int ans=0;
        while(head!=null)
        {
            ans=ans*2;
            ans=ans+head.val;
            head=head.next;
        }
        return ans;
    }
}