Add solution #1601

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,411 LeetCode solutions in JavaScript
+# 1,412 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1236,6 +1236,7 @@
 1598|[Crawler Log Folder](./solutions/1598-crawler-log-folder.js)|Easy|
 1599|[Maximum Profit of Operating a Centennial Wheel](./solutions/1599-maximum-profit-of-operating-a-centennial-wheel.js)|Medium|
 1600|[Throne Inheritance](./solutions/1600-throne-inheritance.js)|Medium|
+1601|[Maximum Number of Achievable Transfer Requests](./solutions/1601-maximum-number-of-achievable-transfer-requests.js)|Hard|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|
 1668|[Maximum Repeating Substring](./solutions/1668-maximum-repeating-substring.js)|Easy|
 1669|[Merge In Between Linked Lists](./solutions/1669-merge-in-between-linked-lists.js)|Medium|

solutions/1601-maximum-number-of-achievable-transfer-requests.js

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+/**
+ * 1601. Maximum Number of Achievable Transfer Requests
+ * https://leetcode.com/problems/maximum-number-of-achievable-transfer-requests/
+ * Difficulty: Hard
+ *
+ * We have n buildings numbered from 0 to n - 1. Each building has a number of employees.
+ * It's transfer season, and some employees want to change the building they reside in.
+ *
+ * You are given an array requests where requests[i] = [fromi, toi] represents an employee's
+ * request to transfer from building fromi to building toi.
+ *
+ * All buildings are full, so a list of requests is achievable only if for each building, the
+ * net change in employee transfers is zero. This means the number of employees leaving is
+ * equal to the number of employees moving in. For example if n = 3 and two employees are
+ * leaving building 0, one is leaving building 1, and one is leaving building 2, there should
+ * be two employees moving to building 0, one employee moving to building 1, and one employee
+ * moving to building 2.
+ *
+ * Return the maximum number of achievable requests.
+ */
+
+/**
+ * @param {number} n
+ * @param {number[][]} requests
+ * @return {number}
+ */
+var maximumRequests = function(n, requests) {
+  let maxAchievable = 0;
+  tryCombination(0, 0, new Array(n).fill(0));
+  return maxAchievable;
+
+  function tryCombination(index, count, balance) {
+    if (index === requests.length) {
+      if (balance.every(val => val === 0)) {
+        maxAchievable = Math.max(maxAchievable, count);
+      }
+      return;
+    }
+
+    const [from, to] = requests[index];
+    balance[from]--;
+    balance[to]++;
+    tryCombination(index + 1, count + 1, balance);
+    balance[from]++;
+    balance[to]--;
+
+    tryCombination(index + 1, count, balance);
+  }
+};