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
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.
Example 1:
Input:
["TaskManager", "add", "edit", "execTop", "rmv", "add", "execTop"]
[[[[1, 101, 10], [2, 102, 20], [3, 103, 15]]], [4, 104, 5], [102, 8], [], [101], [5, 105, 15], []]
Output:
[null, null, null, 3, null, null, 5]
Explanation
TaskManager taskManager = new TaskManager([[1, 101, 10], [2, 102, 20], [3, 103, 15]]); // Initializes with three tasks for Users 1, 2, and 3.
taskManager.add(4, 104, 5); // Adds task 104 with priority 5 for User 4.
taskManager.edit(102, 8); // Updates priority of task 102 to 8.
taskManager.execTop(); // return 3. Executes task 103 for User 3.
taskManager.rmv(101); // Removes task 101 from the system.
taskManager.add(5, 105, 15); // Adds task 105 with priority 15 for User 5.
taskManager.execTop(); // return 5. Executes task 105 for User 5.
Constraints:
1 <= tasks.length <= 105
0 <= userId <= 105
0 <= taskId <= 105
0 <= priority <= 109
0 <= newPriority <= 109
At most 2 * 105 calls will be made in total to add, edit, rmv, and execTop methods.
The input is generated such that taskId will be valid.
设计任务管理器。
一个任务管理器系统可以让用户管理他们的任务，每个任务有一个优先级。这个系统需要高效地处理添加、修改、执行和删除任务的操作。请你设计一个 TaskManager 类：
TaskManager(vector<vector
>& tasks) 初始化任务管理器，初始化的数组格式为 [userId, taskId, priority] ，表示给 userId 添加一个优先级为 priority 的任务 taskId 。 void add(int userId, int taskId, int priority) 表示给用户 userId 添加一个优先级为 priority 的任务 taskId ，输入 保证 taskId 不在系统中。
void edit(int taskId, int newPriority) 更新已经存在的任务 taskId 的优先级为 newPriority 。输入 保证 taskId 存在于系统中。
void rmv(int taskId) 从系统中删除任务 taskId 。输入 保证 taskId 存在于系统中。
int execTop() 执行所有用户的任务中优先级 最高 的任务，如果有多个任务优先级相同且都为 最高 ，执行 taskId 最大的一个任务。执行完任务后，taskId 从系统中 删除 。同时请你返回这个任务所属的用户 userId 。如果不存在任何任务，返回 -1 。
注意 ，一个用户可能被安排多个任务。
思路
这是一道设计题，思路如下。
注意 edit 函数，因为需要对 taskId 的优先级做出修改，所以这里考虑用 hashmap 存储 <taskId, [userId, priority]> 这个信息。以taskId为 key。
因为 execTop() 函数要执行所有用户的任务中优先级 最高 的任务，所以必然牵涉到一个有序的 hashset，这里我用一个最大堆<taskId, priority>处理，堆顶元素是priority最高的任务。
复杂度
参见代码注释。
代码
Java实现
class TaskManager {// tasks, [userId, taskId, priority]// map, <taskId, [userId, priority]>HashMap<Integer, int[]> map = new HashMap<>();// pq, [taskId, priority]// 最大堆，priority大的在堆顶，否则taskId大的在堆顶PriorityQueue<int[]> queue = new PriorityQueue<>((a, b) -> {if (a[1] != b[1]) {return b[1] - a[1];}return b[0] - a[0];});public TaskManager(List<List<Integer>> tasks) {for (List<Integer> task : tasks) {add(task.get(0), task.get(1), task.get(2));}}public void add(int userId, int taskId, int priority) {map.put(taskId, new int[] { userId, priority });queue.offer(new int[] { taskId, priority });}public void edit(int taskId, int newPriority) {// [taskId, prioritys]int[] e = map.get(taskId);e[1] = newPriority; // 更新最新优先级queue.offer(new int[] { taskId, newPriority }); // 推入新副本，先不要管没有删除的那个priority}public void rmv(int taskId) {// 懒删除，不管堆里map.remove(taskId);}public int execTop() {while (!queue.isEmpty()) {int[] cur = queue.poll();int taskId = cur[0];int priority = cur[1];if (!map.containsKey(taskId)) {continue; // 已被删除}int[] e = map.get(taskId);if (e[1] != priority) {continue; // 已被更新（旧版本）}map.remove(taskId); // 执行后移除，因为taskId是唯一的return e[0]; // 返回 userId}return -1;}
}/*** Your TaskManager object will be instantiated and called as such:* TaskManager obj = new TaskManager(tasks);* obj.add(userId,taskId,priority);* obj.edit(taskId,newPriority);* obj.rmv(taskId);* int param_4 = obj.execTop();*/
