Add maximum-product-subarray solution

maximum-product-subarray/joon.py

@@ -0,0 +1,18 @@
+from typing import List
+
+
+class Solution:
+    # Time: O(n)
+    # Space: O(n)
+    def maxProduct(self, nums: List[int]) -> int:
+        maxProducts = [nums[0]]
+        minProducts = [nums[0]]
+        # Store all max/minProducts[i]: the max/min product of all subarrays that have nums[i] as the last element.
+        # Time: O(n)
+        # Space: O(n)
+        for num in nums[1:]:
+            newMaxProduct = max(maxProducts[-1] * num, minProducts[-1] * num, num)
+            newMinProduct = min(maxProducts[-1] * num, minProducts[-1] * num, num)
+            maxProducts.append(newMaxProduct)
+            minProducts.append(newMinProduct)
+        return max(maxProducts)