Create 309-Best-Time-To-Buy-and-Sell-Stock-With-Cooldown.py

Author: neetcode-gh

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

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+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        # State: Buying or Selling?
+        # If Buy -> i + 1
+        # If Sell -> i + 2
+        
+        dp = {} # key=(i, buying) val=max_profit
+        
+        def dfs(i, buying):
+            if i >= len(prices):
+                return 0
+            if (i, buying) in dp:
+                return dp[(i, buying)]
+            
+            cooldown = dfs(i + 1, buying)
+            if buying:
+                buy = dfs(i + 1, not buying) - prices[i]
+                dp[(i, buying)] = max(buy, cooldown)
+            else:
+                sell = dfs(i + 2, not buying) + prices[i]
+                dp[(i, buying)] = max(sell, cooldown)
+            return dp[(i, buying)]
+        
+        return dfs(0, True)