solve: maximumProductSubarray

Author: GaggleHelena

maximum-product-subarray/yolophg.py

@@ -0,0 +1,25 @@
+# Time Complexity: O(N) - just one pass through the array, so it's linear time.
+# Space Complexity: O(1) - no extra arrays, just a few variables.
+
+class Solution:
+    def maxProduct(self, nums: List[int]) -> int:
+        # tracking max product from both ends
+        prefix_product, suffix_product = 1, 1  
+        # start with the biggest single number
+        max_product = max(nums)  
+
+        for i in range(len(nums)):
+            # move forward, multiplying
+            prefix_product *= nums[i]  
+            # move backward, multiplying
+            suffix_product *= nums[len(nums) - i - 1]  
+            # update max product
+            max_product = max(max_product, prefix_product, suffix_product)
+
+            # if hit zero, reset to 1 (zero kills the product chain)
+            if prefix_product == 0:
+                prefix_product = 1
+            if suffix_product == 0:
+                suffix_product = 1
+
+        return max_product