Brexit

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Stack;

/**
 *
 * @author juliuuus
 */
public class Main {
    static int valtioita;
    static int yhteyksia;
    static int koti;
    static int lahtija;
    static int[] alkupNaapuriMaara;
    static int[] naapureita;
    static boolean[] poistunut;
    static int[][] yhteydet;
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
//        IO io = new IO();
//        int solmujenMaara = io.nextInt();
//        int yhteyksienMaara = io.nextInt();
//        int kotimaa = io.nextInt();
//        int lahtija = io.nextInt();
//        HashMap<Integer, Solmu> solmut = new HashMap<>();
//
//        for (int i = 1; i <= solmujenMaara; i++) {
//            solmut.put(i, new Solmu(i));
//        }
//
//        for (int i = 0; i < yhteyksienMaara; i++) {
//            Solmu solmu1 = solmut.get(io.nextInt());
//            Solmu solmu2 = solmut.get(io.nextInt());
//
//            solmu1.addNeighbor(solmu2);
//            solmu2.addNeighbor(solmu1);
//
//        }
//
//        solmut.get(kotimaa).setLahtija(true);
//        solmut.get(lahtija).poistu();
//
//        System.out.println(solmut.get(kotimaa).poistettu ? "leave" : "stay");
//
//        io.close();
        IO io = new IO();
        valtioita = io.nextInt();
        yhteyksia = io.nextInt();
        koti = io.nextInt();
        lahtija = io.nextInt();

        alkupNaapuriMaara = new int[valtioita + 1];
        naapureita = new int[valtioita + 1];
        poistunut = new boolean[valtioita + 1];

        yhteydet = new int[valtioita + 1][valtioita + 1];

        for (int i = 0; i < yhteyksia; i++) {
            int a = io.nextInt();
            int b = io.nextInt();

            yhteydet[a][b] = 1;
            yhteydet[b][a] = 1;

            alkupNaapuriMaara[a]++;
            alkupNaapuriMaara[b]++;

            naapureita[a]++;
            naapureita[b]++;
        }

        
        
        poistu(lahtija);
        if(poistunut[koti]) {
            io.println("leave");
        } else {
            io.println("stay");
        }
        
        io.close();

    }
    
    public static void poistu(int lahtija) {
        poistunut[lahtija] = true;
        for (int i = 1; i <= valtioita; i++) {
            if (yhteydet[lahtija][i] == 1) {
                yhteydet[lahtija][i] = 0;
                naapureita[i]--;

                if ((1.0 * naapureita[i] / alkupNaapuriMaara[i]) <= 0.5) {
                    if(i == koti) {
                        poistunut[koti] = true;
                        break;
                    }
                    poistu(i);
                }
            }
        }
    }

}

class Solmu {

    int origneighbours;
    List<Solmu> neighbours;
    boolean poistettu;
    int name;
    boolean target;
//    private int neigbours;

    public Solmu(int name) {
        this.name = name;
        neighbours = new ArrayList<>();
        origneighbours = 0;
        poistettu = false;
        target = false;
    }

    public void addNeighbor(Solmu n) {
        neighbours.add(n);
        origneighbours++;
    }

    public boolean poistunko() {
        return (1.0 * neighbours.size() / origneighbours) <= 0.5;
    }

    public void poistu() {

        poistettu = true;
        if (target) {
            return;
        }
        for (Solmu s : neighbours) {
            if (s.poistettu) {
                continue;
            }
//            neighbours.remove(s);
            s.deleteNeighbor(this);

        }
        neighbours.clear();
    }

    public void deleteNeighbor(Solmu n) {
        if (neighbours.contains(n)) {
            neighbours.remove(n);
        }
        if (poistunko()) {
            poistu();
        }
    }

    public void setLahtija(boolean l) {
        target = l;
    }

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 18

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 19

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 20

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 21

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 22

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 26

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 27

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 28

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 29

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 30

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 31

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 32

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 33

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 34

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)

Test 35

Verdict: RUNTIME ERROR

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
	at Main.main(Main.java:67)