Add solution #817

Author: JoshCrozier

Diff for: README.md

@@ -625,6 +625,7 @@
 814|[Binary Tree Pruning](./0814-binary-tree-pruning.js)|Medium|
 815|[Bus Routes](./0815-bus-routes.js)|Hard|
 816|[Ambiguous Coordinates](./0816-ambiguous-coordinates.js)|Medium|
+817|[Linked List Components](./0817-linked-list-components.js)|Medium|
 819|[Most Common Word](./0819-most-common-word.js)|Easy|
 821|[Shortest Distance to a Character](./0821-shortest-distance-to-a-character.js)|Easy|
 824|[Goat Latin](./0824-goat-latin.js)|Easy|

Diff for: solutions/0817-linked-list-components.js

@@ -0,0 +1,44 @@
+/**
+ * 817. Linked List Components
+ * https://leetcode.com/problems/linked-list-components/
+ * Difficulty: Medium
+ *
+ * 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.
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number[]} nums
+ * @return {number}
+ */
+var numComponents = function(head, nums) {
+  const numSet = new Set(nums);
+  let componentCount = 0;
+  let inComponent = false;
+
+  let current = head;
+  while (current) {
+    if (numSet.has(current.val)) {
+      if (!inComponent) {
+        componentCount++;
+        inComponent = true;
+      }
+    } else {
+      inComponent = false;
+    }
+    current = current.next;
+  }
+
+  return componentCount;
+};