817. Linked List Components LeetCode Solution

In this guide, you will get 817. Linked List Components LeetCode Solution with the best time and space complexity. The solution to Linked List Components problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Table of Contents

1. Problem Statement
2. Complexity Analysis
3. Linked List Components solution in C++
4. Linked List Components solution in Java
5. Linked List Components solution in Python
6. Additional Resources

Problem Statement of Linked List Components

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:

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:

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 <= 104
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.

Complexity Analysis

• Time Complexity: O(n)
• Space Complexity: O(n)

817. Linked List Components LeetCode Solution in C++

class Solution {
 public:
  int numComponents(ListNode* head, vector<int>& nums) {
    int ans = 0;
    unordered_set<int> setNums{nums.begin(), nums.end()};

    for (; head; head = head->next)
      if (setNums.contains(head->val) &&
          (!head->next || !setNums.contains(head->next->val)))
        ++ans;

    return ans;
  }
};
/* code provided by PROGIEZ */

817. Linked List Components LeetCode Solution in Java

class Solution {
  public int numComponents(ListNode head, int[] nums) {
    int ans = 0;
    Set<Integer> setNums = new HashSet<>();

    for (final int g : nums)
      setNums.add(g);

    for (; head != null; head = head.next)
      if (setNums.contains(head.val) && (head.next == null || !setNums.contains(head.next.val)))
        ++ans;

    return ans;
  }
}
// code provided by PROGIEZ

817. Linked List Components LeetCode Solution in Python

class Solution:
  def numComponents(self, head: ListNode | None, nums: list[int]) -> int:
    ans = 0
    numsSet = set(nums)

    while head:
      if head.val in numsSet and (
              head.next == None or head.next.val not in numsSet):
        ans += 1
      head = head.next

    return ans
 # code by PROGIEZ

Additional Resources

• Explore all LeetCode problem solutions at Progiez here
• Explore all problems on LeetCode website here

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