solve(w02): 238. Product of Array Except Self

Author: jeongwoo903

product-of-array-except-self/jeongwoo903.js

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+/*
+ * 시간 복잡도: O(n)
+ * 공간 복잡도: O(n)
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+
+var productExceptSelf = function(nums) {
+  const lefts = nums.reduce((products, num, i) => {
+      products.push(i === 0 ? 1 : products[i - 1] * nums[i - 1]);
+      return products;
+    }, []
+  );
+
+  return nums.reduceRight((result, num, i) => {
+      const rights = i === nums.length - 1 ? 1 : result.rightProduct * nums[i + 1];
+      result.products[i] *= rights;
+      result.rightProduct = rights;
+      return result;
+    }, { products: lefts, rights: 1 }
+  ).products;
+};