Definition for singly-linked list.

Solved at: 220925

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: $O(1)$