03. Decimal Equivalent of Binary Linked List

The problem can be found at the following link: Question Link

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++)

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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