https://leetcode.com/problems/linked-list-components

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

Example 2:

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

Solution:

Algorithm

Scanning through the list, if node.val is in G and node.next.val isn't (including if node.next is null), then this must be the end of a connected component.

For example, if the list is 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7, and G = [0, 2, 3, 5, 7], then when scanning through the list, we fulfill the above condition at 0, 3, 5, 7, for a total answer of 4.

总结：Description中寻找的是连通的结果，而Solution中寻找的是非连通的结果。