Convert Binary Number in a Linked List to Integer (E)

題目

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

Example 3:

Input: head = [1]
Output: 1

Example 4:

Input: head = [1,0,0,1,0,0,1,1,1,0,0,0,0,0,0]
Output: 18880

Example 5:

Input: head = [0,0]
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.

題意

給定一個用來表示二進位制數的連結串列，要求求出這個數。

思路

和求十進位制一樣。

程式碼實現

Java

class Solution {
    public int getDecimalValue(ListNode head) {
        int num = 0;

        while (head != null) {
            num = num * 2 + head.val;
            head = head.next;
        }

        return num;
    }
}