Add solution #1339

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,239 LeetCode solutions in JavaScript
+# 1,240 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1016,6 +1016,7 @@
 1335|[Minimum Difficulty of a Job Schedule](./solutions/1335-minimum-difficulty-of-a-job-schedule.js)|Hard|
 1337|[The K Weakest Rows in a Matrix](./solutions/1337-the-k-weakest-rows-in-a-matrix.js)|Easy|
 1338|[Reduce Array Size to The Half](./solutions/1338-reduce-array-size-to-the-half.js)|Medium|
+1339|[Maximum Product of Splitted Binary Tree](./solutions/1339-maximum-product-of-splitted-binary-tree.js)|Medium|
 1342|[Number of Steps to Reduce a Number to Zero](./solutions/1342-number-of-steps-to-reduce-a-number-to-zero.js)|Easy|
 1351|[Count Negative Numbers in a Sorted Matrix](./solutions/1351-count-negative-numbers-in-a-sorted-matrix.js)|Easy|
 1352|[Product of the Last K Numbers](./solutions/1352-product-of-the-last-k-numbers.js)|Medium|

solutions/1339-maximum-product-of-splitted-binary-tree.js

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+/**
+ * 1339. Maximum Product of Splitted Binary Tree
+ * https://leetcode.com/problems/maximum-product-of-splitted-binary-tree/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, split the binary tree into two subtrees by removing one edge
+ * such that the product of the sums of the subtrees is maximized.
+ *
+ * Return the maximum product of the sums of the two subtrees. Since the answer may be too large,
+ * return it modulo 109 + 7.
+ *
+ * Note that you need to maximize the answer before taking the mod and not after taking it.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+var maxProduct = function(root) {
+  const sums = [];
+  const MOD = 1e9 + 7;
+  const total = calculateSum(root);
+  let maxProd = 0;
+
+  for (const sum of sums) {
+    maxProd = Math.max(maxProd, sum * (total - sum));
+  }
+
+  return maxProd % MOD;
+
+  function calculateSum(node) {
+    if (!node) return 0;
+    const leftSum = calculateSum(node.left);
+    const rightSum = calculateSum(node.right);
+    const totalSum = node.val + leftSum + rightSum;
+    sums.push(totalSum);
+    return totalSum;
+  }
+};