Add solution #309

Author: JoshCrozier

README.md

@@ -236,6 +236,7 @@
 297|[Serialize and Deserialize Binary Tree](./0297-serialize-and-deserialize-binary-tree.js)|Hard|
 303|[Range Sum Query - Immutable](./0303-range-sum-query-immutable.js)|Easy|
 306|[Additive Number](./0306-additive-number.js)|Medium|
+309|[Best Time to Buy and Sell Stock with Cooldown](./0309-best-time-to-buy-and-sell-stock-with-cooldown.js)|Medium|
 316|[Remove Duplicate Letters](./0316-remove-duplicate-letters.js)|Medium|
 318|[Maximum Product of Word Lengths](./0318-maximum-product-of-word-lengths.js)|Medium|
 322|[Coin Change](./0322-coin-change.js)|Medium|

solutions/0309-best-time-to-buy-and-sell-stock-with-cooldown.js

@@ -0,0 +1,31 @@
+/**
+ * 309. Best Time to Buy and Sell Stock with Cooldown
+ * https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/
+ * Difficulty: Medium
+ *
+ * You are given an array prices where prices[i] is the price of a given stock on the ith day.
+ *
+ * Find the maximum profit you can achieve. You may complete as many transactions as you like
+ * (i.e., buy one and sell one share of the stock multiple times) with the following restrictions:
+ * - After you sell your stock, you cannot buy stock on the next day (i.e., cooldown one day).
+ *
+ * Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock
+ * before you buy again).
+ */
+
+/**
+ * @param {number[]} prices
+ * @return {number}
+ */
+var maxProfit = function(prices) {
+  let result = 0;
+  let remaining = 0;
+
+  for (let i = 0, limit = -Infinity; i < prices.length; i++) {
+    limit = Math.max(limit, remaining - prices[i]);
+    remaining = Math.max(remaining, result);
+    result = limit + prices[i];
+  }
+
+  return Math.max(result, remaining);
+};