Problem of The Day: Convert Binary Number in a Linked List to Integer

Problem Statement

leetcode problem link

Brute Force

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def getDecimalValue(self, head: Optional[ListNode]) -> int:
        curr = head
        string = []
        while curr:
            string.append(str(curr.val))
            curr = curr.next
        return int(''.join(string), 2)

Editorial

class Solution:
    def getDecimalValue(self, head: ListNode) -> int:
        num = head.val
        while head.next:
            num = (num << 1) | head.next.val
            head = head.next
        return num