Challenge: Two Workers

Lab Java Advanced 30 points

Read n. Start two threads: one adds up 1 to n/2, the other adds up n/2 + 1 to n (n/2 is integer division). Wait for both with join(), then print each part and the total.

Input

One whole number n (2 ≤ n ≤ 1000000).

Output

Part 1: <sum>
Part 2: <sum>
Total: <sum>

Example

Input

Output

Part 1: 15
Part 2: 40
Total: 55

Sample input available Sample output available

Editor

Java

Hints

A lambda can only use local variables that never change (n and mid are fine).

Store each thread's answer in a static field.

Use long – the total for a million is bigger than an int can hold.

Solution explanation

Each thread writes its own field, so they never fight over the same variable, and join() makes sure both are done before we print.

Show solution

import java.util.Scanner;

public class Main {
    static long part1, part2;

    public static void main(String[] args) throws InterruptedException {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int mid = n / 2;
        Thread t1 = new Thread(() -> {
            long s = 0;
            for (int i = 1; i <= mid; i++) s += i;
            part1 = s;
        });
        Thread t2 = new Thread(() -> {
            long s = 0;
            for (int i = mid + 1; i <= n; i++) s += i;
            part2 = s;
        });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println("Part 1: " + part1);
        System.out.println("Part 2: " + part2);
        System.out.println("Total: " + (part1 + part2));
    }
}

Output

Answer