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Formatted question description: https://leetcode.ca/all/817.html

# 817. Linked List Components (Medium)

We are given head, the head node of a linked list containing unique integer values.

We are also given the list G, a subset of the values in the linked list.

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

Example 1:

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


Example 2:

Input:
G = [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.


Note:

• If N is the length of the linked list given by head1 <= N <= 10000.
• The value of each node in the linked list will be in the range [0, N - 1].
• 1 <= G.length <= 10000.
• G is a subset of all values in the linked list.

Companies:

Related Topics:

## Solution 1.

• /**
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
class Solution {
public int numComponents(ListNode head, int[] G) {
Set<Integer> subset = new HashSet<Integer>();
for (int value : G)
boolean inComponent = false;
int components = 0;
while (node != null) {
int value = node.val;
if (subset.contains(value)) {
if (!inComponent) {
inComponent = true;
components++;
}
} else {
if (inComponent)
inComponent = false;
}
node = node.next;
}
return components;
}
}

############

/**
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode() {}
*     ListNode(int val) { this.val = val; }
*     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public int numComponents(ListNode head, int[] nums) {
int ans = 0;
Set<Integer> s = new HashSet<>();
for (int v : nums) {
}
}
ans += head != null ? 1 : 0;
}
}
return ans;
}
}

• // OJ: https://leetcode.com/problems/linked-list-components/
// Time: O(N)
// Space: O(N)
class Solution {
public:
int numComponents(ListNode* head, vector<int>& G) {
unordered_set<int> s(G.begin(), G.end());
int ans = 0;
while (true) {
++ans;
}
return ans;
}
};

• # Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
def numComponents(self, head: Optional[ListNode], nums: List[int]) -> int:
ans = 0
s = set(nums)
ans += head is not None
return ans

############

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
"""
:type G: List[int]
:rtype: int
"""
groups = 0
subset = set(G)
groups += 1
return groups

• /**
* type ListNode struct {
*     Val int
*     Next *ListNode
* }
*/
func numComponents(head *ListNode, nums []int) int {
s := map[int]bool{}
for _, v := range nums {
s[v] = true
}
ans := 0
}
ans++
}
}
}
return ans
}

• /**
* class ListNode {
*     val: number
*     next: ListNode | null
*     constructor(val?: number, next?: ListNode | null) {
*         this.val = (val===undefined ? 0 : val)
*         this.next = (next===undefined ? null : next)
*     }
* }
*/

function numComponents(head: ListNode | null, nums: number[]): number {
const set = new Set<number>(nums);
let res = 0;
let inSet = false;
while (cur != null) {
if (set.has(cur.val)) {
if (!inSet) {
inSet = true;
res++;
}
} else {
inSet = false;
}
cur = cur.next;
}
return res;
}


• /**
* function ListNode(val, next) {
*     this.val = (val===undefined ? 0 : val)
*     this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {number[]} nums
* @return {number}
*/
var numComponents = function (head, nums) {
const s = new Set(nums);
let ans = 0;
}
}
}
return ans;
};


• // 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;
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
}
}