817 Linked List Components

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817. Linked List Components​
1. Question
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 inG, where two values are connected if they appear consecutively in the linked list.
Example 1:
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Input:
2
​
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head: 0->1->2->3
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G = [0, 1, 3]
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​
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Output: 2
7
​
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Explanation: 
9
0 and 1 are connected, so [0, 1] and [3] are the two connected components.
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Example 2:
1
Input:
2
head: 0->1->2->3->4
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G = [0, 3, 1, 4]
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​
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Output: 2
6
​
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Explanation: 
8
0 and 1 are connected, 3 and 4 are connected, so [0, 1] and [3, 4] are the two connected components.
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Note:
If Nis the length of the linked list given by head, 1 <= N <= 10000.
The value of each node in the linked list will be in the range[0, N - 1].
1 <= G.length <= 10000.
Gis a subset of all values in the linked list.
2. Implementation
(1) HashSet
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/**
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 * Definition for singly-linked list.
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 * public class ListNode {
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 *     int val;
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 *     ListNode next;
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 *     ListNode(int x) { val = x; }
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 * }
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 */
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class Solution {
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    public int numComponents(ListNode head, int[] G) {
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        Set<Integer> set = new HashSet();
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​
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        for (int node : G) {
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            set.add(node);
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        }
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​
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        int res = 0;
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​
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        while (head != null) {
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            if (set.contains(head.val) && (head.next == null || !set.contains(head.next.val))) {
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                ++res;
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            }
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            head = head.next;
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        }
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        return res;
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    }
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}
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3. Time & Space Complexity
HashSet: 时间复杂度O(n), 空间复杂度O(n)

725 Split Linked List in Parts

148 Sort List

Last modified 2yr ago

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Contents

817. Linked List Components

1. Question

2. Implementation

3. Time & Space Complexity

817. Linked List Components​

1. Question

2. Implementation

3. Time & Space Complexity

817. Linked List Components