import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;

public class SumCalculatorWithForkJoin {

    static class SumTask extends RecursiveTask<Integer> {
        private final int start;
        private final int end;
        private static final int THRESHOLD = 10;

        SumTask(int start, int end) {
            this.start = start;
            this.end = end;
        }

        @Override
        protected Integer compute() {
            if ((end - start) <= THRESHOLD) {
                return calculateSum(start, end);
            } else {
                int mid = start + (end - start) / 2;
                SumTask left = new SumTask(start, mid);
                SumTask right = new SumTask(mid + 1, end);
                left.fork(); // Asynchronously execute the left subtask
                return right.compute() + left.join(); // Compute right subtask and wait for the left subtask
            }
        }

        private int calculateSum(int start, int end) {
            int sum = 0;
            for (int i = start; i <= end; i++) {
                sum += i;
            }
            return sum;
        }
    }

    public static void main(String[] args) {
        ForkJoinPool pool = new ForkJoinPool();
        int n = 100; // Sum of first 100 integers
        int totalSum = pool.invoke(new SumTask(1, n));
        System.out.println("Total sum of first " + n + " integers: " + totalSum);
        pool.shutdown();
    }
}