Solution 1 - Build Number While Traversing

Shift left and add current bit.

TimeComplexity: O(n)

SpaceComplexity: O(1)

""" 1290.1 - Convert Binary Number in a Linked List to Integer - Solution 1 - Traverse """

from typing import Optional

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

class Solution:
    def getDecimalValue(self, head: Optional[ListNode]) -> int:
        res = 0
        cur = head
        while cur:
            res = (res << 1) | cur.val
            cur = cur.next
        return res

package main

type ListNode struct{ Val int; Next *ListNode }

func getDecimalValue(head *ListNode) int {
	res := 0
	for cur := head; cur != nil; cur = cur.Next {
		res = (res << 1) | cur.Val
	}
	return res
}

func main() {}

1290 - Convert Binary Number in a Linked List to Integer

Solution 1 - Build Number While Traversing