不二

问题描述

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.

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.

问题分析

问题比较简单，单链表中的节点要么是0要么是1，是一个整数的二进制表示，需要我们把这个整数计算出来

我们只需初始化一个值ans，每次读取到一个节点值时，将ans左移一位再加上节点值即可

示例代码

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func getDecimalValue(head *ListNode) int {
	ans := 0
	for head != nil {
		ans = ans<<1 + head.Val
		head = head.Next
	}

	return ans
}

原题链接

Convert Binary Number in a Linked List to Integer