diff -r e70a0e3555fb -r 576e7a2861ae src/de/uapcore/sudoku/Solver.java
--- a/src/de/uapcore/sudoku/Solver.java	Fri Feb 01 10:18:47 2013 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,227 +0,0 @@
-/*
- * Copyright 2013 Mike Becker. All rights reserved.
- * 
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- * 
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package de.uapcore.sudoku;
-
-import java.util.ArrayList;
-import java.util.List;
-
-/**
- *
- * @author mike
- */
-public final class Solver {
-    
-    public Solver() {
-    }
-    
-    private Integer fillInCandidate(Field f, List<Integer>[][] candidates, int x, int y) {
-        Integer c = candidates[x][y].remove(0);
-        f.setCellValue(x, y, c);
-        f.setCellModified(x, y, true);
-        for (int i = 0 ; i < 9 ; i++) {
-            candidates[x][i].remove(c);
-            candidates[i][y].remove(c);
-        }
-        for (int i = 0 ; i < 3 ; i++) {
-            for (int j = 0 ; j < 3 ; j++) {
-                candidates[x-x%3+i][y-y%3+j].remove(c);
-            }
-        }
-        return c;
-    }
-    
-    private void makeBackup(List<Integer>[][] candidates, List<Integer>[][] candidatesBackup) {
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                candidatesBackup[x][y] = new ArrayList<>(9);
-                candidatesBackup[x][y].addAll(candidates[x][y]);
-            }
-        }
-    }
-    
-    private void makeBackup(Field f, int[][] fieldBackup) {
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                fieldBackup[x][y] = f.getCellValue(x, y);
-            }
-        }
-    }
-    
-    private void restoreBackup(Field f, int[][] fieldBackup) {
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                f.setCellValue(x, y, fieldBackup[x][y]);
-            }
-        }
-    }
-    
-    private void restoreBackup(List<Integer>[][] candidates, List<Integer>[][] candidatesBackup) {
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                candidates[x][y].clear();
-                candidates[x][y].addAll(candidatesBackup[x][y]);
-            }
-        }
-    }
-    
-    private boolean solve(Field f, List<Integer>[][] candidates) {
-        
-        // Make backup
-        List<Integer>[][] candidatesBackup = new List[9][9];
-        int[][] fieldBackup = new int[9][9];
-        makeBackup(candidates, candidatesBackup);
-        makeBackup(f, fieldBackup);
-        
-        // Fill in distinct solutions
-        boolean fillDistinct;
-        do {
-            fillDistinct = false;
-            for (int x = 0 ; x < 9 ; x++) {
-                for (int y = 0 ; y < 9 ; y++) {
-                    if (f.isCellEmpty(x, y) && candidates[x][y].size() == 1) {
-                        fillInCandidate(f, candidates, x, y);
-                        fillDistinct = true;
-                    }
-                }
-            }
-        } while (fillDistinct);
-        
-        // Try out remaining candidates
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                if (f.isCellEmpty(x, y)) {
-                    while (candidates[x][y].size() > 0) {
-                        List<Integer>[][] cb = new List[9][9];
-                        makeBackup(candidates, cb);
-                        Integer c = fillInCandidate(f, candidates, x, y);
-                        if (solve(f, candidates)) {
-                            break;
-                        } else {
-                            f.clearCellValue(x, y);
-                            restoreBackup(candidates, cb);
-                            // Remove current candidate anyway
-                            candidates[x][y].remove(c);
-                        }
-                    }
-                }
-                if (f.isCellEmpty(x, y)) {
-                    restoreBackup(f, fieldBackup);
-                    restoreBackup(candidates, candidatesBackup);
-                    return false;
-                }
-            }
-        }
-        
-        return true;
-    }
-    
-    public boolean solve(Field f) {
-        
-        // Calculate initial candidates
-        List<Integer> candidates[][] = new List[9][9];
-        for (int x = 0 ; x < 9 ; x++) {
-            for (int y = 0 ; y < 9 ; y++) {
-                candidates[x][y] = new ArrayList<>(9);
-                if (f.getCellValue(x, y) == 0) {
-                    // All numbers are candidates
-                    for (int c = 1 ; c <= 9 ; c++) {
-                        candidates[x][y].add(c);
-                    }
-                    // Remove row duplicates
-                    int[] line = f.getRow(y);
-                    for (Integer c : line) {
-                        candidates[x][y].remove(c);
-                    }
-                    // Remove column duplicates
-                    line = f.getColumn(x);
-                    for (Integer c : line) {
-                        candidates[x][y].remove(c);
-                    }
-                    // Remove square duplicates
-                    int[][] square = f.getSquare(x/3, y/3);
-                    for (int[] sq : square) {
-                        for (Integer c : sq) {
-                            candidates[x][y].remove(c);
-                        }
-                    }
-                }
-            }
-        }
-        
-        // Backtrack
-        return solve(f, candidates);
-    }
-    
-    public boolean check(Field f) {
-        int line[];
-        for (int i = 0 ; i < 9 ; i++) {
-            line = f.getRow(i);
-            if (!valid(line)) {
-                return false;
-            }
-            line = f.getColumn(i);
-            if (!valid(line)) {
-                return false;
-            }
-        }
-        
-        int square[][];
-        for (int x = 0 ; x < 3 ; x++) {
-            for (int y = 0 ; y < 3 ; y++) {
-                square = f.getSquare(x, y);
-                if (!valid(square)) {
-                    return false;
-                }
-            }
-        }
-        
-        return true;
-    }
-    
-    private boolean valid(int[] line) {
-        int numbers[];
-        numbers = new int[9];
-        for (int i = 0 ; i < 9 ; i++) {
-            int l = line[i]-1;
-            if (l >= 0) {
-                if ((++numbers[l]) > 1) {
-                    return false;
-                }
-            }
-        }
-        
-        return true;
-    }
-    
-    private boolean valid(int[][] square) {
-        int[] line = new int[9];
-        for (int x = 0 ; x < 3 ; x++) {
-            System.arraycopy(square[x], 0, line, 3*x, 3);
-        }
-        return valid(line);
-    }
-}