DLX Algorithm for Solving Sudoku game Java

Use the DLX algorithm to perform a Sudoku game.
Java beginners, algorithm code is converted from C code.
DLX. Java is an algorithm class, and Sudoku. Java is an interface class.
It takes less than 10 ms to describe the world's most difficult Sudoku.

Algorithm details

Sudoku MongoDB links Template

Usage

Int n = 9;
DLX = new DLX (N * n + 1, 4 * n );
DLX. setnum (5); // you can obtain a maximum of five solutions. The default value is 2.
DLX. Solve (data); // int data [9] [9];

List <int [] []> solutions = DLX. getsolutions ();

Code download

Https://code.google.com/p/sudoku-dlx/source/checkout

DLX. Java

import java.util.ArrayList;import java.util.List;public class DLX{private static final int ROW = 4096 + 50;private static final int COL = 1024 + 50;private static final int N = 4 * 9 * 9;private static final int m = 3;DLXNode row[] = new DLXNode[ROW];DLXNode col[] = new DLXNode[COL];DLXNode head;private int n;private int num = 2;private int size[] = new int[COL];int data[][] = new int[9][9];List<int[][]> solutions;public DLX(int r, int c){n = m * m;head = new DLXNode(r, c);head.U = head.D = head.L = head.R = head;for (int i = 0; i < c; ++i){col[i] = new DLXNode(r, i);col[i].L = head;col[i].R = head.R;col[i].L.R = col[i].R.L = col[i];col[i].U = col[i].D = col[i];size[i] = 0;}for (int i = r - 1; i > -1; --i){row[i] = new DLXNode(i, c);row[i].U = head;row[i].D = head.D;row[i].U.D = row[i].D.U = row[i];row[i].L = row[i].R = row[i];}}public void addNode(int r, int c){DLXNode p = new DLXNode(r, c);p.R = row[r];p.L = row[r].L;p.L.R = p.R.L = p;p.U = col[c];p.D = col[c].D;p.U.D = p.D.U = p;++size[c];}public void addNode(int i, int j, int k){int r = (i * n + j) * n + k;addNode(r, i * n + k - 1);addNode(r, n * n + j * n + k - 1);addNode(r, 2 * n * n + block(i, j) * n + k - 1);addNode(r, 3 * n * n + i * n + j);}int block(int x, int y){return x / m * m + y / m;}public void cover(int c){if (c == N)return;col[c].delLR();DLXNode R, C;for (C = col[c].D; C != col[c]; C = C.D){if (C.c == N)continue;for (R = C.L; R != C; R = R.L){if (R.c == N)continue;--size[R.c];R.delUD();}C.delLR();}}public void resume(int c){if (c == N)return;DLXNode R, C;for (C = col[c].U; C != col[c]; C = C.U){if (C.c == N)continue;C.resumeLR();for (R = C.R; R != C; R = R.R){if (R.c == N)continue;++size[R.c];R.resumeUD();}}col[c].resumeLR();}public boolean solve(int depth){if (head.L == head){int solution[][] = new int[n][n];for (int i = 0; i < n; ++i)for (int j = 0; j < n; ++j)solution[i][j] = data[i][j];solutions.add(solution);if (solutions.size() == num)return true;return false;}int minSize = 1 << 30;int c = -1;DLXNode p;for (p = head.L; p != head; p = p.L)if (size[p.c] < minSize){minSize = size[p.c];c = p.c;}cover(c);for (p = col[c].D; p != col[c]; p = p.D){DLXNode cell;p.R.L = p;for (cell = p.L; cell != p; cell = cell.L){cover(cell.c);}p.R.L = p.L;int rr = p.r - 1;data[rr / (n * n)][rr / n % n] = rr % n + 1;if (solve(depth + 1))return true;p.L.R = p;for (cell = p.R; cell != p; cell = cell.R)resume(cell.c);p.L.R = p.R;}resume(c);return false;}public boolean solve(int data[][]){init(data);return solve(0);}public void init(int data[][]){solutions = new ArrayList<int[][]>();int i, j, k;for (i = 0; i < n; ++i)for (j = 0; j < n; ++j){if (data[i][j] > 0){addNode(i, j, data[i][j]);} else{for (k = 1; k <= n; ++k)addNode(i, j, k);}}}public void setNum(int num){this.num = num;}public int getNum(){return num;}public List<int[][]> getSolutions(){return solutions;}}class DLXNode{int r,c;DLXNode U,D,L,R;DLXNode(){r = c = 0;}DLXNode(int r, int c){this.r = r;this.c = c;}DLXNode(int r, int c, DLXNode U, DLXNode D, DLXNode L, DLXNode R){this.r = r;this.c = c;this.U = U;this.D = D;this.L = L;this.R = R;}public void delLR(){L.R = R;R.L = L;}public void delUD(){U.D = D;D.U = U;}public void resumeLR(){L.R = R.L = this;}public void resumeUD(){U.D = D.U = this;}}

Sudoku. java

import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.LineBorder;import javax.swing.border.TitledBorder;import javax.swing.plaf.basic.BasicArrowButton;import javax.swing.text.*;public class Sudoku extends JPanel{/** *  */private static final long serialVersionUID = 1L;private static final int width = 9;private static final int height = 9;private int data[][] = new int[height][width];private String infoStr = "";JButton solve = new JButton("Solve"), reset = new JButton("Reset"), clean = new JButton("Clean");BasicArrowButton right = new BasicArrowButton(BasicArrowButton.EAST), left = new BasicArrowButton(BasicArrowButton.WEST);JTextField sudokus[][] = new JTextField[height][width];JTextPane info = new JTextPane();java.util.List<int[][]> solutions;private int solutionIdx = 0;Sudoku(){setLayout(null);for (int r = 0; r < 3; ++r){for (int c = 0; c < 3; ++c){JPanel jp = new JPanel();jp.setLayout(null);jp.setBounds(r * 95 + 5, c * 95 + 5, 95, 95);jp.setBorder(new LineBorder(Color.black));for (int x = 0; x < 3; ++x)for (int y = 0; y < 3; ++y){int j = r * 3 + x, i = c * 3 + y;sudokus[i][j] = new JTextField();sudokus[i][j].setBounds(30 * x + 5, 30 * y + 5, 25, 25);sudokus[i][j].setDocument(new NumberLenghtLimitedDmt(1));jp.add(sudokus[i][j]);}add(jp);}}solve.setBounds(85, 300, 75, 25);solve.addActionListener(new SolveAL());add(solve);reset.setBounds(175, 300, 75, 25);reset.addActionListener(new ResetAL());add(reset);clean.setBounds(265, 300, 75, 25);clean.addActionListener(new cleanAL());add(clean);left.setVisible(false);left.setBounds(170, 330, 50, 25);left.addActionListener(new prevAL());add(left);right.setVisible(false);right.setBounds(230, 330, 50, 25);right.addActionListener(new nextAL());add(right);JScrollPane jsp = new JScrollPane(info);info.setEditable(false);jsp.setBounds(300, 5, 140, 285);jsp.setBorder(new TitledBorder("Info"));add(jsp);}public boolean solve(){int i, j;for (i = 0; i < height; ++i){for (j = 0; j < width; ++j){try{data[i][j] = Integer.parseInt(sudokus[i][j].getText());sudokus[i][j].setEditable(false);} catch (NumberFormatException e){data[i][j] = 0;sudokus[i][j].setEnabled(false);}}}int n = 9;long startTime = System.currentTimeMillis();DLX dlx = new DLX(n * n * n + 1, 4 * n * n);dlx.setNum(5);dlx.solve(data);solutions = dlx.getSolutions();if (solutions.size() > 1)infoStr += "Find multi solutions.\n";else if (solutions.size() > 0)infoStr += "Find one solution.\n";elseinfoStr += "Cannot find a solution.\n";infoStr += "Used time: " + (System.currentTimeMillis() - startTime) + " ms\n";return update();}public void reset(int data[][]){solve.setEnabled(true);int i, j;for (i = 0; i < height; ++i){for (j = 0; j < width; ++j){sudokus[i][j].setEnabled(true);sudokus[i][j].setEditable(true);if (data[i][j] == 0){sudokus[i][j].setText("");} else{sudokus[i][j].setText(Integer.toString(data[i][j]));}}}}boolean update(){info.setText(infoStr);if (solutionIdx >= solutions.size())return false;left.setVisible(true);right.setVisible(true);int i, j;int solution[][] = solutions.get(solutionIdx);for (i = 0; i < height; ++i){for (j = 0; j < width; ++j){sudokus[i][j].setText(Integer.toString(solution[i][j]));}}return true;}public static void inFrame(JPanel jp, int width, int height){String title = "Sudoku";JFrame frame = new JFrame(title);frame.addWindowListener(new WindowAdapter() {public void windowClosing(WindowEvent e){System.exit(0);}});frame.getContentPane().add(jp, BorderLayout.CENTER);frame.setLocationByPlatform(true);frame.setSize(width, height);frame.setResizable(false);frame.setVisible(true);}public static void main(String[] args){int data[][] = { { 8, 0, 0, 0, 0, 0, 0, 0, 0 }, { 0, 0, 3, 6, 0, 0, 0, 0, 0 }, { 0, 7, 0, 0, 9, 0, 2, 0, 0 },{ 0, 5, 0, 0, 0, 7, 0, 0, 0 }, { 0, 0, 0, 0, 4, 5, 7, 0, 0 }, { 0, 0, 0, 1, 0, 0, 0, 3, 0 },{ 0, 0, 1, 0, 0, 0, 0, 6, 8 }, { 0, 0, 8, 5, 0, 0, 0, 1, 0 }, { 0, 9, 0, 0, 0, 0, 4, 0, 0 }, };Sudoku sudoku = new Sudoku();sudoku.reset(data);inFrame(sudoku, 450, 400);}class SolveAL implements ActionListener{public void actionPerformed(ActionEvent e){infoStr += "Start solve this sudoku.\n";info.setText(infoStr);solve.setEnabled(false);solve();}}class ResetAL implements ActionListener{public void actionPerformed(ActionEvent e){infoStr += "Reset sudoku data.\n";info.setText(infoStr);left.setVisible(false);right.setVisible(false);reset(data);}}class cleanAL implements ActionListener{public void actionPerformed(ActionEvent e){infoStr = "Clean sudoku data.\n";info.setText(infoStr);solve.setEnabled(true);left.setVisible(false);right.setVisible(false);int i, j;for (i = 0; i < height; ++i){for (j = 0; j < width; ++j){sudokus[i][j].setText("");sudokus[i][j].setEnabled(true);sudokus[i][j].setEditable(true);}}}}class prevAL implements ActionListener{public void actionPerformed(ActionEvent e){int size = solutions.size();if(size > 0){solutionIdx = (solutionIdx - 1 + size) % size;infoStr += "The " + (solutionIdx+1) + "th solution.\n";update();}}}class nextAL implements ActionListener{public void actionPerformed(ActionEvent e){int size = solutions.size();if(size > 0){solutionIdx = (solutionIdx + 1) % size;infoStr += "The " + (solutionIdx+1) + "th solution.\n";update();}}}class NumberLenghtLimitedDmt extends PlainDocument{/** *  */private static final long serialVersionUID = 1L;private int limit;public NumberLenghtLimitedDmt(int limit){super();this.limit = limit;}public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException{if (str == null){return;}if ((getLength() + str.length()) <= limit){char[] upper = str.toCharArray();int length = 0;for (int i = 0; i < upper.length; i++){if (upper[i] >= '0' && upper[i] <= '9'){upper[length++] = upper[i];}}super.insertString(offset, new String(upper, 0, length), attr);}}}}