solve: maximum product subarray

Author: sounmind

maximum-product-subarray/evan.py

@@ -0,0 +1,35 @@
+from typing import List
+
+
+class Solution:
+    def maxProduct(self, nums: List[int]) -> int:
+        if not nums:
+            return 0
+
+        local_max_product = nums[0]
+        min_product = nums[0]
+        global_max_product = nums[0]
+
+        for i in range(1, len(nums)):
+            current = nums[i]
+
+            temp_max = max(
+                # the current element alone could be the new maximum product subarray.
+                current,
+
+                # extending the previous maximum product subarray to include the current element.
+                local_max_product * current,
+
+                # if the current element is negative, multiplying it by the previous minimum product subarray
+                # (which could be a large negative number) might result in a large positive number,
+                # thus becoming the new maximum product.
+                min_product * current,
+            )
+            min_product = min(
+                current, local_max_product * current, min_product * current
+            )
+            local_max_product = temp_max
+
+            global_max_product = max(global_max_product, local_max_product)
+
+        return global_max_product