solve: product of array except self

Author: sounmind

product-of-array-except-self/evan.js

@@ -0,0 +1,33 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var productExceptSelf = function (nums) {
+  const length = nums.length;
+  const result = Array(length).fill(1);
+
+  let leftProduct = 1;
+  for (let i = 0; i < length; i++) {
+    result[i] = leftProduct;
+    leftProduct *= nums[i];
+  }
+
+  let rightProduct = 1;
+  for (let i = length - 1; i >= 0; i--) {
+    result[i] *= rightProduct;
+    rightProduct *= nums[i];
+  }
+
+  return result;
+};
+
+/**
+ * Time Complexity: O(n)
+ * The algorithm iterates through the nums array twice (two separate loops), each taking O(n) time.
+ * Hence, the overall time complexity is O(2n), which simplifies to O(n).
+ *
+ * Space Complexity: O(1)
+ * The algorithm uses a constant amount of extra space for the leftProduct and rightProduct variables.
+ * The result array is not considered extra space as it is required for the output.
+ * Therefore, the extra space complexity is O(1).
+ */