product-of-array-except-self solution & complexity

Author: sungjinwi

product-of-array-except-self/sungjinwi.py

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+"""
+	TC : for문 두번 반복하므로 O(2N)
+		-> O(N)
+	SC : answer 배열 외에 추가적인 메모리는 factor 변수 하나이므로
+		-> O(1)
+"""
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        answer = [1] * len(nums)
+        factor = 1
+        for i in range(len(nums) - 1) :
+            factor *= nums[i]
+            answer[i + 1] *= factor
+        factor = 1
+        for i in range(len(nums) - 1, 0, -1) :
+            factor *= nums[i]
+            answer[i - 1] *= factor
+        return answer