edit: move DaleStudy#270 solution

maximum-product-subarray/EGON.py

@@ -0,0 +1,67 @@
+from typing import List
+from unittest import TestCase, main
+
+
+class Solution:
+    def maxProduct(self, nums: List[int]) -> int:
+        return self.solveWithDP(nums)
+
+    """
+    Runtime: 71 ms (Beats 61.13%)
+    Time Complexity: O(n)
+        - dp 배열 초기화를 위한 nums.copy()에 O(n)
+        - range(1, L) 조회하며 조건에 따라 연산에 O(n - 1)
+        - range(L) 조회하며 max 계산에 O(n)
+        > O(n) + O(n - 1) + O(n) ~= O(n)
+
+    Memory: 17.75 MB (Beats 11.09%)
+    Space Complexity: O(n)
+        - 크기가 n인 배열 2개 사용했으므로 2 * O(n)
+        > O(2n) ~= O(n)
+    """
+    def solveWithDP(self, nums: List[int]) -> int:
+        L = len(nums)
+        forward_product, backward_product = nums.copy(), nums.copy()
+        for i in range(1, L):
+            if forward_product[i - 1] != 0:
+                forward_product[i] *= forward_product[i - 1]
+
+            if backward_product[L - i] != 0:
+                backward_product[L - i - 1] *= backward_product[L - i]
+
+        result = nums[0]
+        for i in range(L):
+            result = max(result, forward_product[i], backward_product[i])
+
+        return result
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        nums = [2,3,-2,4]
+        output = 6
+        self.assertEqual(Solution.maxProduct(Solution(), nums), output)
+
+    def test_2(self):
+        nums = [-2,0,-1]
+        output = 0
+        self.assertEqual(Solution.maxProduct(Solution(), nums), output)
+
+    def test_3(self):
+        nums = [-2]
+        output = -2
+        self.assertEqual(Solution.maxProduct(Solution(), nums), output)
+
+    def test_4(self):
+        nums = [0,-3,-2,-3,-2,2,-3,0,1,-1]
+        output = 72
+        self.assertEqual(Solution.maxProduct(Solution(), nums), output)
+
+    def test_5(self):
+        nums = [7, -2, -4]
+        output = 56
+        self.assertEqual(Solution.maxProduct(Solution(), nums), output)
+
+
+if __name__ == '__main__':
+    main()