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Author: hogan-tech

3652-best-time-to-buy-and-sell-stock-using-strategy/3652-best-time-to-buy-and-sell-stock-using-strategy.py

@@ -0,0 +1,47 @@
+# time complexity: O(n)
+# space complexity: O(n)
+from typing import List
+
+
+class Solution:
+    def maxProfit(self, prices: List[int], strategy: List[int], k: int) -> int:
+        n = len(prices)
+
+        base = sum(p * s for p, s in zip(prices, strategy))
+
+        half = k // 2
+
+        conPrefix = [0]*(n+1)
+        for i in range(n):
+            conPrefix[i+1] = conPrefix[i] + strategy[i]*prices[i]
+
+        pricePrefix = [0]*(n+1)
+        for i in range(n):
+            pricePrefix[i+1] = pricePrefix[i] + prices[i]
+
+        bestDelta = 0
+
+        for l in range(n-k+1):
+            mid = l+half
+            r = l+k
+
+            loss = conPrefix[mid] - conPrefix[l]
+
+            gain = (pricePrefix[r] - pricePrefix[mid]) - \
+                (conPrefix[r] - conPrefix[mid])
+
+            delta = -loss + gain
+            if delta > bestDelta:
+                bestDelta = delta
+
+        return base + bestDelta
+
+
+prices = [4, 2, 8]
+strategy = [-1, 0, 1]
+k = 2
+print(Solution().maxProfit(prices, strategy, k))
+prices = [5, 4, 3]
+strategy = [1, 1, 0]
+k = 2
+print(Solution().maxProfit(prices, strategy, k))