59 lines
1.9 KiB
Java
59 lines
1.9 KiB
Java
|
|
public class KnightsTourBoard
|
|
{
|
|
protected int m_width;
|
|
protected int m_height;
|
|
protected int[][] m_board;
|
|
|
|
KnightsTourBoard(int width, int height)
|
|
{
|
|
m_width = width;
|
|
m_height = height;
|
|
m_board = new int[width][height];
|
|
}
|
|
|
|
public int getWidth() { return m_width; }
|
|
public int getHeight() { return m_height; }
|
|
public int getStepAt(int x, int y) { return m_board[x][y]; }
|
|
|
|
public boolean tour(int startx, int starty)
|
|
{
|
|
for (int x = 0; x < m_width; x++)
|
|
for (int y = 0; y < m_height; y++)
|
|
m_board[x][y] = 0;
|
|
m_board[startx][starty] = 1;
|
|
return tourFrom(2, startx, starty);
|
|
}
|
|
|
|
private boolean tourFrom(int nextStep, int startx, int starty)
|
|
{
|
|
// System.out.println("tourFrom(" + nextStep + ", " +
|
|
// startx + ", " + starty + ")");
|
|
final int[] xoffsets = {-2, -1, 1, 2, -2, -1, 1, 2};
|
|
final int[] yoffsets = {-1, -2, -2, -1, 1, 2, 2, 1};
|
|
|
|
for (int moveIndex = 0; moveIndex < 8; moveIndex++)
|
|
{
|
|
int x = startx + xoffsets[moveIndex];
|
|
int y = starty + yoffsets[moveIndex];
|
|
|
|
if (x >= 0 && x < m_width && y >= 0 && y < m_height)
|
|
{
|
|
if (m_board[x][y] == 0) /* if space has not been visited yet */
|
|
{
|
|
m_board[x][y] = nextStep; /* we just took step number
|
|
* nextStop, stop if that is all
|
|
* we needed to do */
|
|
if (nextStep == m_width * m_height)
|
|
return true;
|
|
if (tourFrom(nextStep + 1, x, y)) /* else walk from there */
|
|
return true;
|
|
m_board[x][y] = 0; /* this step did not lead to a solution */
|
|
}
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
}
|