Laskettelukeskus

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Objects;
import java.util.Scanner;
 
public class Datatahti {
    private static class Rinne {
        ArrayList<Rinne> children = new ArrayList<>();
        int maara;
    }
 
    public static long rec(Rinne rinne) {
        long total = rinne.maara;
        long childrenNeeds = 0;
        for (Rinne child : rinne.children) {
            childrenNeeds += rec(child);
        }
        total += Math.max(0, childrenNeeds - total);
        return total;
    }
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(Objects.requireNonNull(Datatahti.class.getResourceAsStream("/input.txt"))));
 
        int n = Integer.parseInt(reader.readLine());
        Rinne[] rinteet = new Rinne[n + 1];
        for (int i = 0; i < rinteet.length; i++) {
            rinteet[i] = new Rinne();
        }
        for (int i = 0; i < n - 1; i++) {
            String[] line = reader.readLine().split(" ");
            int a = Integer.parseInt(line[0]);
            int b = Integer.parseInt(line[1]);
            //I should realy use c++....
 
            rinteet[a].children.add(rinteet[b]);
        }
        String[] maarat = reader.readLine().split(" ");
        for (int i = 0; i < n; i++) {
            rinteet[i+1].maara = Integer.parseInt(maarat[i]);
        }
 
        System.out.println(rec(rinteet[1]));
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 2

Verdict: ACCEPTED

Test 5

Group: 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED