> For the complete documentation index, see [llms.txt](https://gl01.gitbook.io/gfg-editorials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl01.gitbook.io/gfg-editorials/2024/02-2024-feb-2/03-decimal-equivalent-of-binary-linked-list.md).

# 03. Decimal Equivalent of Binary Linked List

The problem can be found at the following link: [Question Link](https://www.geeksforgeeks.org/problems/decimal-equivalent-of-binary-linked-list/1)

## My Approach

* I am iterating through the linked list, treating it as a binary representation of a number.
* At each step, I shift the current result left by one bit (multiply by 2) and add the current node's data.
* I also take care to update the result modulo 1e9 + 7 to avoid overflow.

## Time and Auxiliary Space Complexity

* **Time Complexity** : `O(N)`, where N is the number of nodes in the linked list.
* **Auxiliary Space Complexity** : O(1)

## Code (C++)

```cpp
class Solution {
public:
    long long unsigned int decimalValue(Node *head)
    {
        long long unsigned int out = 0, mod = 1e9 + 7;
        Node* temp = head;

        while (temp) {
            out = (out << 1) % mod;
            out = (out + temp->data) % mod;
            temp = temp->next;
        }

        return out;
    }
};
```

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