SO robot

package robotti2;

import java.util.ArrayList;
import java.util.Scanner;
import static robotti2.Robotti2.*;

class Maze {

    public final int[] layout;
    public final int[] distances;
    public int pos;
    public boolean isAlive;

    public Maze(int[] layout) {
        this.layout = layout;
        this.distances = createDistanceMatrix();
        this.pos = 0;
        this.isAlive = true;
    }

    public int getDistance() {
        return distances[pos];
    }

    public int getDistance(int dir) {
        if (!canMove(layout, pos, dir)) return getDistance();
        return distances[pos+dir];
    }

    private int[] createDistanceMatrix() {
        int a[] = new int[16];
        for (int i = 0; i < 16; i++)
            a[i] = (layout[i] == 1) ? 255 : 99;

        a[15] = 0;

        boolean f;
        do {

            f = false;

            for (int i = 0; i < 16; i++) {
                if (a[i] < 255) {

                    int min = a[i];

                    for (int m : mov) {
//                        if (i+m < 0 || i+m >= 16 || a[i+m] == -1) continue;

                        if (canMove(layout, i, m) && a[i+m] < min)
                            min = a[i+m];

                    }

                    if (a[i] > min + 1) {
                        a[i] = min + 1;
                        f = true;
                    }

                }
            }

        } while (f);

        return a;
    }

    public void move(int dir) {
        int npos = pos + dir;
        if (npos < 0 || npos >= 16) return;
        if (layout[npos] == 1) return;
        if (dir == 1 && pos % 4 == 3) return;
        if (dir == -1 && pos % 4 == 0) return;
        if (Math.abs((npos - pos) % 4) > 1) return;

        pos = npos;
        if (pos == 15) this.isAlive = false;
    }

    public void print() {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++)
                System.out.printf("%-2s", i*4 + j == pos ? "x" : layout[i*4 + j]);
            System.out.println();
        }
        System.out.println();
    }
}

public class Robotti2 {

    public static final int R = 1;
    public static final int L = -1;
    public static final int U = -4;
    public static final int D = 4;
    public static final int[] mov = new int[] {R,L,U,D};

    public static ArrayList<Maze> mazes = new ArrayList<>();

    public static boolean isSolution(String s) {
        int remaining = mazes.size();

        for (char c : s.toCharArray()) {
            for (Maze maze : mazes) {
                if (!maze.isAlive) continue;

                if (c == 'R')
                    maze.move(R);
                if (c == 'L')
                    maze.move(L);
                if (c == 'U')
                    maze.move(U);
                if (c == 'D')
                    maze.move(D);

                if (!maze.isAlive) {
                    remaining--;
                }

            }
        }

        for (Maze maze : mazes) maze.isAlive = true;

        System.out.println(remaining);
        return remaining == 0;
    }

    public static void main(String[] args) {
        generateMazes("0");
        handGame();
    }

    public static void handGame() {
        int remaining = mazes.size();

        String seq = "";
        Scanner sc = new Scanner(System.in);
        while (remaining > 0) {
            System.out.println("Sequence: " + seq + " Length: " + seq.length());
            System.out.println("---------------------");
            System.out.println("Removed: " + remaining);
            System.out.println("Remaining: " + remaining);

            int _a = 0;
            int[] a = new int[16];
            int[] p = new int[16];
            for (Maze maze : mazes) {
                if (!maze.isAlive) continue;

                for (int i = 0; i < 16; i++) {
                    a[i] += maze.layout[i];
                    _a += a[i];
                }

                p[maze.pos]++;
            }

            System.out.println("");
            System.out.printf("%-36s", "    | Obstacles");
            System.out.printf(" | Current positions\n");
            for (int i = 0; i < 4; i++) {
                System.out.print("    |    ");
                for (int j = 0; j < 4; j++) {
                    System.out.printf("%4d", a[i*4 + j]);
                    System.out.print("  ");
                }
                System.out.print("    |    ");
                for (int j = 0; j < 4; j++) {
                    System.out.printf("%4d", p[i*4 + j]);
                    System.out.print("  ");
                }
                System.out.println();
            }
            System.out.println();
            System.out.print("Command: ");
            String cmd = sc.nextLine();
            seq += cmd.toUpperCase();

            for (Maze maze : mazes) {
                if (!maze.isAlive) continue;

                if (cmd.equals("d"))
                    maze.move(R);
                if (cmd.equals("a"))
                    maze.move(L);
                if (cmd.equals("w"))
                    maze.move(U);
                if (cmd.equals("s"))
                    maze.move(D);

                if (!maze.isAlive) {
                    remaining--;
                }

            }
        }
    }

    public static void generateMazes(String layout) {
        if (layout.length() == 16) {
            if (layout.charAt(15) == '1') return;

            int[] a = new int[16];
            for (int i = 0; i < 16; i++) a[i] = Character.digit(layout.charAt(i), 10);
            if (solutionExists(a, 15)) mazes.add(new Maze(a));
            return;
        }

        generateMazes(layout+'1');
        generateMazes(layout+'0');
    }

    public static boolean solutionExists(int[] a, int k) {
        if (a[0] == 2) return true;
        if (a[k] == 2) return false;

        for (int m : mov) {
            if (canMove(a, k, m)) {
                a[k] = 2;
                boolean f = solutionExists(a, k+m);
                a[k] = 0;
                if (f) return true;
            }
        }

        return false;
    }

    public static boolean canMove(int[] a, int pos, int dir) {
        int npos = pos + dir;
        if (npos < 0 || npos >= 16) return false;
        if (a[npos] == 1) return false;
        if (dir == 1 && pos % 4 == 3) return false;
        if (dir == -1 && pos % 4 == 0) return false;
        return Math.abs((npos - pos) % 4) <= 1;
    }

    public static int[] cpy(int[] arr) {
        int[] a = new int[arr.length];
        System.arraycopy(arr, 0, a, 0, a.length);
        return a;
    }

}