Read a Binary Integer From Native List Nodes
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
The nonempty singly linked list begins with its most significant binary digit. Every node value is 0 or 1. Return the represented integer in decimal, reading head to tail.
```cpp
class Solution {
public:
int getDecimalValue(ListNode* head);
};
```
### Examples
**Example 1:**
```text
Input: head = [1,1,0]
Output: 6
Explanation: Binary110 equals4+2=6.
```
**Example 2:**
```text
Input: head = [0,0,1,1]
Output: 3
Explanation: Leading zeros do not change the value of binary0011.
```
### Constraints
- The linked list is nonempty and has at most 30 nodes.
- Every node contains 0 or 1.
### Contract considerations
Retain `ListNode* head`; the example arrays display node values and do not replace the native linked-list API.
```hint Read the boundary condition
Which end holds the most significant digit, and are leading zero-valued nodes allowed?
```
### Boundary reminders
Retain `ListNode* head`; the example arrays display node values and do not replace the native linked-list API.
Overview: Read a Binary Integer From Native List Nodes. The nonempty singly linked list begins with its most significant binary digit.
