Add solution #3408

Author: JoshCrozier

README.md

@@ -2732,6 +2732,7 @@
 3403|[Find the Lexicographically Largest String From the Box I](./solutions/3403-find-the-lexicographically-largest-string-from-the-box-i.js)|Medium|
 3405|[Count the Number of Arrays with K Matching Adjacent Elements](./solutions/3405-count-the-number-of-arrays-with-k-matching-adjacent-elements.js)|Hard|
 3406|[Find the Lexicographically Largest String From the Box II](./solutions/3406-find-the-lexicographically-largest-string-from-the-box-ii.js)|Hard|
+3408|[Design Task Manager](./solutions/3408-design-task-manager.js)|Medium|
 3416|[Subsequences with a Unique Middle Mode II](./solutions/3416-subsequences-with-a-unique-middle-mode-ii.js)|Hard|
 3422|[Minimum Operations to Make Subarray Elements Equal](./solutions/3422-minimum-operations-to-make-subarray-elements-equal.js)|Medium|
 3423|[Maximum Difference Between Adjacent Elements in a Circular Array](./solutions/3423-maximum-difference-between-adjacent-elements-in-a-circular-array.js)|Easy|

solutions/3408-design-task-manager.js

@@ -0,0 +1,91 @@
+/**
+ * 3408. Design Task Manager
+ * https://leetcode.com/problems/design-task-manager/
+ * Difficulty: Medium
+ *
+ * There is a task management system that allows users to manage their tasks, each associated
+ * with a priority. The system should efficiently handle adding, modifying, executing, and
+ * removing tasks.
+ *
+ * Implement the TaskManager class:
+ * - TaskManager(vector<vector<int>>& tasks) initializes the task manager with a list of
+ *   user-task-priority triples. Each element in the input list is of the form [userId,
+ *   taskId, priority], which adds a task to the specified user with the given priority.
+ * - void add(int userId, int taskId, int priority) adds a task with the specified taskId
+ *   and priority to the user with userId. It is guaranteed that taskId does not exist in
+ *   the system.
+ * - void edit(int taskId, int newPriority) updates the priority of the existing taskId to
+ *   newPriority. It is guaranteed that taskId exists in the system.
+ * - void rmv(int taskId) removes the task identified by taskId from the system. It is
+ *   guaranteed that taskId exists in the system.
+ * - int execTop() executes the task with the highest priority across all users. If there
+ *   are multiple tasks with the same highest priority, execute the one with the highest
+ *   taskId. After executing, the taskId is removed from the system. Return the userId
+ *   associated with the executed task. If no tasks are available, return -1.
+ *
+ * Note that a user may be assigned multiple tasks.
+ */
+
+/**
+ * @param {number[][]} tasks
+ */
+var TaskManager = function(tasks) {
+  this.taskRegistry = {};
+  this.priorityHeap = new PriorityQueue((a, b) => {
+    return a.priority !== b.priority ? b.priority - a.priority : b.taskId - a.taskId;
+  });
+
+  for (const [userId, taskId, priority] of tasks) {
+    this.taskRegistry[taskId] = { userId, priority, version: 1 };
+    this.priorityHeap.enqueue({ taskId, priority, version: 1 });
+  }
+};
+
+/**
+ * @param {number} userId
+ * @param {number} taskId
+ * @param {number} priority
+ * @return {void}
+ */
+TaskManager.prototype.add = function(userId, taskId, priority) {
+  this.taskRegistry[taskId] = { userId, priority, version: 1 };
+  this.priorityHeap.enqueue({ taskId, priority, version: 1 });
+};
+
+/**
+ * @param {number} taskId
+ * @param {number} newPriority
+ * @return {void}
+ */
+TaskManager.prototype.edit = function(taskId, newPriority) {
+  const currentTask = this.taskRegistry[taskId];
+  currentTask.priority = newPriority;
+  currentTask.version++;
+  this.priorityHeap.enqueue({ taskId, priority: newPriority, version: currentTask.version });
+};
+
+/**
+ * @param {number} taskId
+ * @return {void}
+ */
+TaskManager.prototype.rmv = function(taskId) {
+  delete this.taskRegistry[taskId];
+};
+
+
+/**
+ * @return {number}
+ */
+TaskManager.prototype.execTop = function() {
+  while (!this.priorityHeap.isEmpty()) {
+    const { taskId, priority, version } = this.priorityHeap.dequeue();
+    const activeTask = this.taskRegistry[taskId];
+
+    if (activeTask && activeTask.priority === priority && activeTask.version === version) {
+      const executedUserId = activeTask.userId;
+      delete this.taskRegistry[taskId];
+      return executedUserId;
+    }
+  }
+  return -1;
+};