Convert Binary Number in a Linked List to Integer

给一个linked list, 里面是0和1,二进制 求变成整数后的数.

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public int getDecimalValue(ListNode head) {
        int res = 0;
        while(head != null) {
            res = (res << 1) | head.val;
            head = head.next;
        }
        return res;
    }
}