Merge pull request neetcode-gh#338 from shehanck/main

leetcode-309 solution in Java

java/309-Best-Time-To-Buy-and-Sell-Stock-With-Cooldown.java

@@ -0,0 +1,29 @@
+class Solution {
+ public int maxProfit(int[] prices) {
+ Map<String, Integer> cache = new HashMap<>();
+ return dfs(prices, cache, 0, true);
+ }
+
+ public int dfs(int[] prices, Map<String, Integer> cache, int index, boolean buying) {
+ if (index >= prices.length) {
+ return 0;
+ }
+ String key = index+"-"+buying;
+
+ if (cache.containsKey(key)) {
+ return cache.get(key);
+ }
+
+ int cooldown = dfs(prices, cache, index + 1, buying);
+ int buyOsell = Integer.MIN_VALUE;
+
+ if (buying) {
+ buyOsell = dfs(prices, cache, index + 1, !buying) - prices[index];
+ } else {
+ buyOsell = dfs(prices, cache, index + 2, !buying) + prices[index];
+ }
+
+ cache.put(key, Math.max(buyOsell, cooldown)); 
+ return cache.get(key);
+ }
+}