Reddit DailyProgrammer Challenge #133 - Chain Reaction

ChainReaction.java

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;


public class ChainReaction {

    static int stepCount = 0;

    enum Direction {
        UP,
        DOWN,
        LEFT,
        RIGHT
    }

    static class Element {

        int posX;
        int posY;
        int radius;
        char name;
        boolean isActive;
        Set<Direction> directions = new HashSet<Direction>();
        Element[][] grid;

        void propagate() {
            if (!isActive) {
                name = 'X';
                drawGrid(grid.length, grid);
                isActive = true;
                for (Direction direction : directions) {
                    try {
                        int tempRadius = radius;
                        if (direction == Direction.UP) {
                            int tempPos = 1;
                            while (tempRadius-- > 0) {
                                if (grid[posX][posY - tempPos] != null) {
                                    grid[posX][posY - tempPos].propagate();
                                }
                                tempPos++;
                            }
                        } else if (direction == Direction.DOWN) {
                            int tempPos = 1;
                            while (tempRadius-- > 0) {
                                if (grid[posX][posY + tempPos] != null) {
                                    grid[posX][posY + tempPos].propagate();
                                }
                                tempPos++;
                            }
                        } else if (direction == Direction.LEFT) {
                            int tempPos = 1;
                            while (tempRadius-- > 0) {
                                if (grid[posX - tempPos][posY] != null) {
                                    grid[posX - tempPos][posY].propagate();
                                }
                                tempPos++;
                            }
                        } else if (direction == Direction.RIGHT) {
                            int tempPos = 1;
                            while (tempRadius-- > 0) {
                                if (grid[posX + tempPos][posY] != null) {
                                    grid[posX + tempPos][posY].propagate();
                                }
                                tempPos++;
                            }
                        }
                    } catch (IndexOutOfBoundsException e) {
                    }
                }
            }
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] numbers = sc.nextLine().split(" ");
        int gridSize = Integer.parseInt(numbers[1]);
        Element[][] grid = new Element[gridSize][gridSize];
        List<Element> elements = new ArrayList<Element>();
        char elementName = 'A';
        for (int i = 0; i < Integer.parseInt(numbers[0]); i++) {
            String[] elementLineItems = sc.nextLine().split(" ");

            Element element = new Element();
            element.grid = grid;
            element.name = elementName++;
            element.posX = Integer.parseInt(elementLineItems[0]);
            element.posY = Integer.parseInt(elementLineItems[1]);
            element.radius = Integer.parseInt(elementLineItems[2]);

            if (elementLineItems[3].toUpperCase().contains("U"))
                element.directions.add(Direction.UP);
            if (elementLineItems[3].toUpperCase().contains("D"))
                element.directions.add(Direction.DOWN);
            if (elementLineItems[3].toUpperCase().contains("L"))
                element.directions.add(Direction.LEFT);
            if (elementLineItems[3].toUpperCase().contains("R"))
                element.directions.add(Direction.RIGHT);

            elements.add(element);
        }
        sc.close();

        for (Element element : elements) {
            grid[element.posX][element.posY] = element;
        }

        drawGrid(gridSize, grid);
        elements.get(0).propagate();
    }

    private static void drawGrid(int gridSize, Element[][] grid) {
        System.out.println("Step " + stepCount++ + ":");
        for (int i = 0; i < gridSize; i++) {
            for (int j = 0; j < gridSize; j++) {
                if (grid[j][i] != null) {
                    System.out.print(grid[j][i].name);
                } else {
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
    }

}