Linked List Components
<p>You are given the <code>head</code> of a linked list containing unique integer values and an integer array <code>nums</code> that is a subset of the linked list values.</p>

<p>Return <em>the number of connected components in </em><code>nums</code><em> where two values are connected if they appear <strong>consecutively</strong> in the linked list</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0800-0899/0817.Linked%20List%20Components/images/lc-linkedlistcom1.jpg" style="width: 424px; height: 65px;" />
<pre>
<strong>Input:</strong> head = [0,1,2,3], nums = [0,1,3]
<strong>Output:</strong> 2
<strong>Explanation:</strong> 0 and 1 are connected, so [0, 1] and [3] are the two connected components.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0800-0899/0817.Linked%20List%20Components/images/lc-linkedlistcom2.jpg" style="width: 544px; height: 65px;" />
<pre>
<strong>Input:</strong> head = [0,1,2,3,4], nums = [0,3,1,4]
<strong>Output:</strong> 2
<strong>Explanation:</strong> 0 and 1 are connected, 3 and 4 are connected, so [0, 1] and [3, 4] are the two connected components.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the linked list is <code>n</code>.</li>
	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
	<li><code>0 &lt;= Node.val &lt; n</code></li>
	<li>All the values <code>Node.val</code> are <strong>unique</strong>.</li>
	<li><code>1 &lt;= nums.length &lt;= n</code></li>
	<li><code>0 &lt;= nums[i] &lt; n</code></li>
	<li>All the values of <code>nums</code> are <strong>unique</strong>.</li>
</ul>
Array; Hash Table; Linked List
// Definition for singly-linked list.
// #[derive(PartialEq, Eq, Clone, Debug)]
// pub struct ListNode {
//   pub val: i32,
//   pub next: Option<Box<ListNode>>
// }
//
// impl ListNode {
//   #[inline]
//   fn new(val: i32) -> Self {
//     ListNode {
//       next: None,
//       val
//     }
//   }
// }
use std::collections::HashSet;
impl Solution {
    pub fn num_components(head: Option<Box<ListNode>>, nums: Vec<i32>) -> i32 {
        let set = nums.into_iter().collect::<HashSet<i32>>();
        let mut res = 0;
        let mut in_set = false;
        let mut cur = &head;
        while let Some(node) = cur {
            if set.contains(&node.val) {
                if !in_set {
                    in_set = true;
                    res += 1;
                }
            } else {
                in_set = false;
            }
            cur = &node.next;
        }
        res
    }
}
