feat: product of array except self

Author: minji-go

product-of-array-except-self/minji-go.java

@@ -0,0 +1,24 @@
+/*
+    Problem: https://leetcode.com/problems/product-of-array-except-self/
+    Description: return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].
+    Concept: Array, Prefix Sum
+    Time Complexity: O(N), Runtime 5ms
+    Space Complexity: O(N), Memory 54.6MB - O(1) except the output array
+*/
+class Solution {
+    public int[] productExceptSelf(int[] nums) {
+        int[] answer = new int[nums.length];
+        Arrays.fill(answer, 1);
+
+        int prefixProduct = 1;
+        int suffixProduct = 1;
+        for(int i=1; i<nums.length; i++){
+            prefixProduct = prefixProduct * nums[i-1];
+            suffixProduct = suffixProduct * nums[nums.length-i];
+            answer[i] *= prefixProduct;
+            answer[nums.length-i-1] *= suffixProduct;
+        }
+
+        return answer;
+    }
+}