adding updates

src/my_project/interviews/google_top_exercises/round_1/08_product_of_array_excep_self.py

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+from typing import List 
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        """
+        Calculate product of all elements except self without division.
+
+        Strategy: Two-pass with prefix and suffix products
+        - First pass: Build prefix products (product of all elements to the left)
+        - Second pass: Build suffix products (product of all elements to the right)
+        - Result[i] = prefix[i] * suffix[i]
+
+        Optimization: Use output array to store prefix, then multiply by suffix in-place
+
+        Time: O(n), Space: O(1) excluding output array
+        """
+
+        n = len(nums)
+        answer = [1] * n
+
+        # First pass: Calculate prefix products
+        # answer[i] contains product of all elements to the left of i
+        prefix = 1
+        for i in range(n):
+            answer[i] = prefix
+            prefix *= nums[i]
+
+        # Second pass: Calculate suffix products and multiply with prefix
+        # For each position, multiply existing prefix with product of all elements to the right
+        suffix = 1
+        for i in range(n - 1, -1, -1):
+            answer[i] *= suffix
+            suffix *= nums[i]
+
+        return answer