1290. Convert Binary Number in a Linked List to Integer

[DNPotapov]

# 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: ListNode) -> int:
        cur = head
        res = ""
        while (cur.next):
            res += str(cur.val)
            cur = cur.next
        res += str(cur.val)
        return int(res,2)

[DNPotapov]

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.

Example 1:

Input: head = [1,0,1] Output: 5 Explanation: (101) in base 2 = (5) in base 10 Example 2:

Input: head = [0] Output: 0

Constraints:

The Linked List is not empty. Number of nodes will not exceed 30. Each node's value is either 0 or 1.