【Leetcode】1290. Convert Binary Number in a Linked List to Integer

題目地址：

https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer/

給定一個只由$0$或$1$構成的鏈表，返回其代表的二進制數。直接模擬就好了。代碼如下：

public class Solution {
    public int getDecimalValue(ListNode head) {
        int res = 0;
        while (head != null) {
            res <<= 1;
            res += head.val;
            head = head.next;
        }
        
        return res;
    }
}

class ListNode {
    int val;
    ListNode next;
    ListNode(int x) {
        val = x;
    }
}

時間複雜度$O(n)$。