Add solution #369

Author: JoshCrozier

README.md

@@ -357,6 +357,7 @@
 366|[Find Leaves of Binary Tree](./solutions/0366-find-leaves-of-binary-tree.js)|Medium|
 367|[Valid Perfect Square](./solutions/0367-valid-perfect-square.js)|Easy|
 368|[Largest Divisible Subset](./solutions/0368-largest-divisible-subset.js)|Medium|
+369|[Plus One Linked List](./solutions/0369-plus-one-linked-list.js)|Medium|
 371|[Sum of Two Integers](./solutions/0371-sum-of-two-integers.js)|Medium|
 372|[Super Pow](./solutions/0372-super-pow.js)|Medium|
 373|[Find K Pairs with Smallest Sums](./solutions/0373-find-k-pairs-with-smallest-sums.js)|Medium|

solutions/0369-plus-one-linked-list.js

@@ -0,0 +1,40 @@
+/**
+ * 369. Plus One Linked List
+ * https://leetcode.com/problems/plus-one-linked-list/
+ * Difficulty: Medium
+ *
+ * Given a non-negative integer represented as a linked list of digits, plus one to the integer.
+ *
+ * The digits are stored such that the most significant digit is at the head of the 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
+ * @return {ListNode}
+ */
+var plusOne = function(head) {
+  const list = new ListNode(0, head);
+  let notNine = list;
+
+  while (head) {
+    if (head.val !== 9) notNine = head;
+    head = head.next;
+  }
+
+  notNine.val++;
+  notNine = notNine.next;
+
+  while (notNine) {
+    notNine.val = 0;
+    notNine = notNine.next;
+  }
+
+  return list.val === 0 ? list.next : list;
+};