求解任务完成所需的最短时间：一种基于扫描线的算法

import java.util.*;

class TaskScheduling {

    static class Event {
        int time;
        int type; // 0: start, 1: end
        int begin;
        int period;

        public Event(int time, int type, int begin, int period) {
            this.time = time;
            this.type = type;
            this.begin = begin;
            this.period = period;
        }
    }

    public static int minTimeToFinishTasks(List<List<Integer>> tasks) {
        List<Event> events = new ArrayList<>();
        for (List<Integer> task : tasks) {
            int begin = task.get(0);
            int end = task.get(1);
            int period = task.get(2);
            events.add(new Event(begin, 0, begin, period)); // Start event
            events.add(new Event(end, 1, begin, period));   // End event
        }

        // Sort events by time, start events before end events if times are equal
        Collections.sort(events, (a, b) -> {
            if (a.time != b.time) {
                return a.time - b.time;
            } else {
                return a.type - b.type; // Start before end
            }
        });

        List<Pair> activeTasks = new ArrayList<>(); // Store (startTime, remainingTime)
        int result = 0;

        for (Event event : events) {
            if (event.type == 0) {
                // Start event
                activeTasks.add(new Pair(event.begin, event.period));
            } else {
                // End event: Find the corresponding start event and update
                int timeNeeded = 0;
                for(Pair task : activeTasks){
                    if(task.startTime == event.begin){
                        timeNeeded = task.remainingTime;
                        break;
                    }
                }

                result += timeNeeded;

                // Remove the completed task and subtract time from remaining tasks
                activeTasks.removeIf(task -> task.startTime == event.begin);
            }
        }

        return result;
    }

    static class Pair {
        int startTime;
        int remainingTime;

        public Pair(int startTime, int remainingTime) {
            this.startTime = startTime;
            this.remainingTime = remainingTime;
        }
    }

    public static void main(String[] args) {
        List<List<Integer>> tasks = new ArrayList<>();
        tasks.add(Arrays.asList(1, 3, 2));
        tasks.add(Arrays.asList(2, 5, 3));
        tasks.add(Arrays.asList(5, 6, 2));

        int minTime = minTimeToFinishTasks(tasks);
        System.out.println("Minimum time to finish tasks: " + minTime); // Output: 4
    }
}