feat(problems): implement product of array except self solution

work/Medium/Array/238.product-of-array-except-self.js

@@ -46,9 +46,22 @@
 */
 
 /**
- * @param {number[]} _nums
+ * @param {number[]} nums
  * @return {number[]}
  */
-var productExceptSelf = function(_nums
-      
+var productExceptSelf = function(nums) {
+  const n = nums.length;
+  const answer = new Array(n).fill(1);
+  const rightArr = new Array(n).fill(1);
+
+  for (let i = 1; i < n; i++) {
+    answer[i] = nums[i - 1] * answer[i - 1];
+  }
+  for (let i = n - 2; i >= 0; i--) {
+    rightArr[i] = nums[i + 1] * rightArr[i + 1];
+  }
+  for (let i = 0; i < n; i++) {
+    answer[i] *= rightArr[i];
+  }
+  return answer;
 };