## Description

LeetCode Problem 817.

You are given the head of a linked list containing unique integer values and an integer array nums that is a subset of the linked list values.

Return the number of connected components in nums where two values are connected if they appear consecutively in the linked list.

Example 1:

``````1
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3
Input: head = [0,1,2,3], nums = [0,1,3]
Output: 2
Explanation: 0 and 1 are connected, so [0, 1] and [3] are the two connected components.
``````

Example 2:

``````1
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3
Input: head = [0,1,2,3,4], nums = [0,3,1,4]
Output: 2
Explanation: 0 and 1 are connected, 3 and 4 are connected, so [0, 1] and [3, 4] are the two connected components.
``````

Constraints:

• The number of nodes in the linked list is n.
• 1 <= n <= 10^4
• 0 <= Node.val < n
• All the values Node.val are unique.
• 1 <= nums.length <= n
• 0 <= nums[i] < n
• All the values of nums are unique.

## Sample C++ Code

``````1
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/**
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode() : val(0), next(nullptr) {}
*     ListNode(int x) : val(x), next(nullptr) {}
*     ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
int numComponents(ListNode* head, vector<int>& nums) {
unordered_set<int> map(nums.begin(),nums.end());
int ans = 0;
bool lastMatch = 0;
lastMatch = 0;
} else {
if (!lastMatch) {
ans++;
lastMatch = 1;
}
}
}
return ans;
}
};
``````