product-of-array-except-self solution

Author: togo26

product-of-array-except-self/togo26.js

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+// TC: O(n) / SC: O(n)
+var productExceptSelf = function (nums) {
+  const left = [1];
+  const right = [1];
+  const result = [];
+
+  for (let i = 1; i < nums.length; i++) {
+    left.push(left[i - 1] * nums[i - 1]);
+  }
+
+  for (let i = nums.length - 1; i > 0; i--) {
+    right.push(right[nums.length - 1 - i] * nums[i]);
+  }
+
+  for (let i = 0, j = nums.length - 1; i < nums.length; i++, j--) {
+    result[i] = left[i] * right[j];
+  }
+
+  return result;
+};
+
+// TC: O(n) / SC: O(1)
+var productExceptSelf = function (nums) {
+  const left = new Array(nums.length).fill(1);
+
+  for (let i = 1; i < nums.length; i++) {
+    left[i] = left[i - 1] * nums[i - 1];
+  }
+
+  let rightProduct = 1;
+  for (let i = nums.length - 1; i >= 0; i--) {
+    left[i] *= rightProduct;
+    rightProduct *= nums[i];
+  }
+
+  return left;
+};