main.go

// Source: https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer
// Title: Convert Binary Number in a Linked List to Integer
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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:**
// https://assets.leetcode.com/uploads/2019/12/05/graph-1.png
//
// ```
// 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`.
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

type ListNode struct {
	Val  int
	Next *ListNode
}

func getDecimalValue(head *ListNode) int {
	ans := 0
	for head != nil {
		ans <<= 1
		ans += head.Val
		head = head.Next
	}
	return ans
}