LeetCode 1290 Convert Binary Number In A Linked List To Integer - Easy

1290. Convert Binary Number In A Linked List To Integer — Easy

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Problem

Binary to Decimal from Linked List: LeetCode 1290 A binary number is represented as a series of 0s and 1s.

In this challenge: the series will be in the form of a singly-linked list. Each node instance, a LinkedListNode has a value, val and a pointer to the next node.

Given a reference to the head of a singly-linked list, convert the binary number represented to a decimal number, for example.

0->1->0->0->1->1->1->null

linkedlist corresponding to the binary number (010011)bin or (19)10

Function Description: Complete the function getNumber in the editor below. The function must return a (long integer)10 representation of the binary number.

getNumber has the following parameters: binary: reference to the head of a singly-linked list of binary digits:

Constraints: 1<= n <= 64 All linkedListNode.val belongs to {0, 1} The decribed (integer)2 < 2^64

Example: 0011010 -> (0011010)bin = (26)10

Solution

### using bitwise operators:
 
# 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:
        num = head.val
        while head.next:
            num = (num << 1) | head.next.val
            head = head.next
        return num