<p>Given <code>head</code> which is a reference node to a singly-linked list. The value of each node in the linked list is either <code>0</code> or <code>1</code>. The linked list holds the binary representation of a number.</p>

<p>Return the <em>decimal value</em> of the number in the linked list.</p>

<p>The <strong>most significant bit</strong> is at the head of the linked list.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/12/05/graph-1.png" style="width: 426px; height: 108px;" />
<pre>
<strong>Input:</strong> head = [1,0,1]
<strong>Output:</strong> 5
<strong>Explanation:</strong> (101) in base 2 = (5) in base 10
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> head = [0]
<strong>Output:</strong> 0
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The Linked List is not empty.</li>
	<li>Number of nodes will not exceed <code>30</code>.</li>
	<li>Each node&#39;s value is either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution {
public:
    /**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode* next;
 * };
 */

int getDecimalValue(struct ListNode* head) {
    struct ListNode* current = head;
    int length = 0;

    // Calculate the length of the linked list
    while (current != NULL) {
        length++;
        current = current->next;
    }

    int decimalValue = 0;
    current = head;

    // Convert binary to decimal
    while (current != NULL) {
        decimalValue += current->val * (1 << (length - 1));
        length--;
        current = current->next;
    }

    return decimalValue;
  }
};
10000