product-of-array-except-self

0238_product-of-array-except-self/python3/solution.py

@@ -0,0 +1,25 @@
+from functools import reduce
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        # We can divide this problem by finding the prefix and
+        # postfix products of a given element and then multiplying
+        # them together
+        result = [0] * len(nums)
+        
+        # Find prefix products, i.e, for ith element, store
+        # product of 0 to a[i - 1]
+        prefix = 1
+        for i, num in enumerate(nums):
+            result[i] = prefix
+            prefix *= num
+        
+        # Find suffix products by iterating from the last, and
+        # combine them with prefix in the same step to reduce cost
+        suffix = 1
+        for i in range(len(nums) - 1, -1, -1):
+            result[i] *= suffix
+            suffix *= nums[i]
+        
+        return result
+