Linked List Components LeetCode solution in C++

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class Solution {
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 public:
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  int numComponents(ListNode *head, vector<int> &nums) {
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    unordered_set<int> s;
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    for (auto &x : nums) s.insert(x);
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    int count = 0;
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    while (head != NULL) {
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      if (s.find(head->val) != s.end()) count++;
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      while (head != NULL && s.find(head->val) != s.end()) {
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        head = head->next;
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      }
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      if (head != NULL) head = head->next;
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    }
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    return count;
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  }
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};