817. Linked List Components 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
class Solution {
    public int numComponents(ListNode head, int[] nums) {
        Set<Integer> set = new HashSet<>();
        for (int num : nums) {
            set.add(num);
        }

        int count = 0;

        ListNode curr = head;
        while (curr != null) {
            if (set.contains(curr.val)) {
                while (curr.next != null && set.contains(curr.next.val)) {
                    curr = curr.next;
                }

                // now: curr.next == null or set.notContains(curr.next.val)
                count++;
            }
            curr = curr.next;
        }

        return count;
    }
}

References

817. Linked List Components