 # 1290 Convert Binary Number in a Linked List to Integer

Solved at: 2022-09-25

## Question​

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.

## Solution​

# Definition for singly-linked list.# class ListNode:#     def __init__(self, val=0, next=None):#         self.val = val#         self.next = nextclass Solution:    def getDecimalValue(self, head: ListNode) -> int:        value = head.val        while head.next:            value *= 2            head = head.next            value += head.val        return value

## Results​

### Runtime​

• 60 ms, faster than 28.54% of Python3 online submissions for Convert Binary Number in a Linked List to Integer.

### Memory Usage​

• 13.9 MB, less than 9.10% of Python3 online submissions for Convert Binary Number in a Linked List to Integer.

## Complexity Analysis​

• Time complexity: $O(n)$
• Space complexity: $O(1)$