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Use pure Java sudoku Suexg (public domain) generator/solver from PlantUML repository.
[sudokuki/sudokuki.git] / src / classes / net / sourceforge / plantuml / sudoku / DLXEngine.java
diff --git a/src/classes/net/sourceforge/plantuml/sudoku/DLXEngine.java b/src/classes/net/sourceforge/plantuml/sudoku/DLXEngine.java
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@@ -0,0 +1,1228 @@
+/****************************************************************************
+ * DLXEngine.java
+ *
+ * Created on den 30 december 2005, 01:04
+ *
+ * DLXEngine
+ * Sudoku puzzle generator and solver based on the suexg and suexk by
+ * Gunter Stertenbrink. Suexg and suexk are C implementations of the
+ * Dancing Links algorithm by Donald Knuth and optimized for performance
+ * which means that certain cleanup work has been done. There is still
+ * lots of these activities left to do, however, the code is nasty and
+ * hard to read - but extremely efficient.
+ *
+ * The code is public domain so feel free to use it.
+ *****************************************************************************/
+
+package net.sourceforge.plantuml.sudoku;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.Date;
+import java.util.Random;
+
+/*******************************************************************************
+ * dlx_solver solve any Sudoku in a fraction of a second. Input is a string of
+ * dots and digits representing the puzzle to solve and output is the solved
+ * puzzle.
+ * 
+ * @author Rolf Sandberg
+ ******************************************************************************/
+class dlx_solver {
+       static final int M = 8; // change this for larger grids. Use symbols as in
+                                                       // L[] below
+       static final int M2 = M * M;
+       static final int M4 = M2 * M2;
+
+       /** Pseudo-random number generator */
+       long MWC() {
+               return random.nextLong();
+       }
+
+       int A0[][] = new int[M2 + 9][M2 + 9], A[][] = new int[M2 + 9][M2 + 9], Rows[] = new int[4 * M4 + 9],
+                       Cols[] = new int[M2 * M4 + 9], Row[][] = new int[4 * M4 + 9][M2 + 9];
+       int Col[][] = new int[M2 * M4 + 9][5], Ur[] = new int[M2 * M4 + 9], Uc[] = new int[4 * M4 + 9], V[] = new int[M2
+                       * M4 + 9];
+       int C[] = new int[M4 + 9], I[] = new int[M4 + 9], T[] = new int[M2 * M4 + 9], P[] = new int[M2 * M4 + 9];
+       int Mr[] = { 0, 1, 63, 1023, 4095, 16383, 46655, 131071, 262143 };
+       int Mc[] = { 0, 1, 63, 511, 1023, 4095, 8191, 16383, 16383 };
+       int Mw[] = { 0, 1, 3, 15, 15, 31, 63, 63, 63 };
+
+       int nocheck = 0, max, _try_;
+       final int rnd = 0;
+       int min, clues, gu, tries;
+       long Node[] = new long[M4 + 9];
+       long nodes, tnodes, solutions, vmax, smax, time0, time1, t1, x1;
+       double xx, yy;
+       int q, a, p, i, i1, j, k, l, r, r1, c, c1, c2, n, N = 0, N2, N4, m, m0, m1, x, y, s;
+       char L[] = { '.', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
+                       'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e',
+                       'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
+                       '#', '*', '~' };
+
+       /** State machine states */
+       static final int M6 = 10;
+       static final int M7 = 11;
+       static final int RESTART = 12;
+       static final int M22 = 13;
+       static final int M3 = 14;
+       static final int M44 = 15;
+       static final int NEXT_TRY = 16;
+       static final int END = 30;
+
+       /**
+        * Solver function. Input parameter: A puzzle to solve Output: The solved
+        * puzzle
+        */
+       String solve(String puzzle) {
+               System.out.println("puzzle = "+puzzle);
+               String result = new String();
+               int STATE = M6;
+
+               vmax = 4000000;
+               smax = 25;
+               p = 1;
+               q = 0;
+
+               if (q > 0) {
+                       vmax = 99999999;
+                       smax = 99999999;
+               }
+
+               N = 3;
+               N2 = N * N;
+               N4 = N2 * N2;
+               m = 4 * N4;
+               n = N2 * N4;
+
+               if (puzzle.length() < N4) {
+                       return "Error, puzzle incomplete";
+               }
+
+               while (STATE != END) {
+                       switch (STATE) {
+                       case M6:
+                               clues = 0;
+                               i = 0;
+                               for (x = 0; x < N2; x++)
+                                       for (y = 0; y < N2; y++) {
+                                               c = puzzle.charAt(x * N2 + y);
+                                               j = 0;
+
+                                               if (c == '-' || c == '.' || c == '0' || c == '*') {
+                                                       A0[x][y] = j;
+                                                       i++;
+                                               } else {
+                                                       while (L[j] != c && j <= N2)
+                                                               j++;
+
+                                                       if (j <= N2) {
+                                                               A0[x][y] = j;
+                                                               if (j > 0)
+                                                                       clues++;
+                                                               i++;
+                                                       }
+                                               }
+                                       }
+
+                               if (clues == N4) {
+                                       clues--;
+                                       A0[1][1] = 0;
+                               }
+
+                               if (p < 8) {
+                                       for (i = 0; i <= N4; i++)
+                                               Node[i] = 0;
+                               }
+                               tnodes = 0;
+
+                       case RESTART:
+                               r = 0;
+                               for (x = 1; x <= N2; x++)
+                                       for (y = 1; y <= N2; y++)
+                                               for (s = 1; s <= N2; s++) {
+                                                       r++;
+                                                       Cols[r] = 4;
+                                                       Col[r][1] = x * N2 - N2 + y;
+                                                       Col[r][4] = (N * ((x - 1) / N) + (y - 1) / N) * N2 + s + N4;
+
+                                                       Col[r][3] = x * N2 - N2 + s + N4 * 2;
+                                                       Col[r][2] = y * N2 - N2 + s + N4 * 3;
+                                               }
+                               for (c = 1; c <= m; c++)
+                                       Rows[c] = 0;
+
+                               for (r = 1; r <= n; r++)
+                                       for (c = 1; c <= Cols[r]; c++) {
+                                               x = Col[r][c];
+                                               Rows[x]++;
+                                               Row[x][Rows[x]] = r;
+                                       }
+
+                               for (x = 0; x < N2; x++)
+                                       for (y = 0; y < N2; y++)
+                                               A[x][y] = A0[x][y];
+
+                               for (i = 0; i <= n; i++)
+                                       Ur[i] = 0;
+                               for (i = 0; i <= m; i++)
+                                       Uc[i] = 0;
+
+                               solutions = 0;
+
+                               for (x = 1; x <= N2; x++)
+                                       for (y = 1; y <= N2; y++)
+                                               if (A[x - 1][y - 1] > 0) {
+                                                       r = x * N4 - N4 + y * N2 - N2 + A[x - 1][y - 1];
+
+                                                       for (j = 1; j <= Cols[r]; j++) {
+                                                               c1 = Col[r][j];
+                                                               if (Uc[c1] > 0 && nocheck == 0) {
+                                                                       STATE = NEXT_TRY;
+                                                                       break;
+                                                               }
+
+                                                               Uc[c1]++;
+
+                                                               for (k = 1; k <= Rows[c1]; k++) {
+                                                                       r1 = Row[c1][k];
+                                                                       Ur[r1]++;
+                                                               }
+                                                       }
+                                                       if (STATE == NEXT_TRY)
+                                                               break;
+                                               }
+                               if (STATE == NEXT_TRY)
+                                       break;
+
+                               if (rnd > 0 && rnd != 17 && rnd != 18)
+                                       shuffle();
+
+                               for (c = 1; c <= m; c++) {
+                                       V[c] = 0;
+                                       for (r = 1; r <= Rows[c]; r++)
+                                               if (Ur[Row[c][r]] == 0)
+                                                       V[c]++;
+                               }
+
+                               i = clues;
+                               nodes = 0;
+                               m0 = 0;
+                               m1 = 0;
+                               gu = 0;
+                               solutions = 0;
+
+                       case M22:
+                               i++;
+                               I[i] = 0;
+                               min = n + 1;
+                               if (i > N4 || m0 > 0) {
+                                       STATE = M44;
+                                       break;
+                               }
+                               if (m1 > 0) {
+                                       C[i] = m1;
+                                       STATE = M3;
+                                       break;
+                               }
+                               for (c = 1; c <= m; c++)
+                                       if (Uc[c] == 0) {
+                                               if (V[c] <= min)
+                                                       c1 = c;
+                                               if (V[c] < min) {
+                                                       min = V[c];
+                                                       C[i] = c;
+                                                       if (min < 2) {
+                                                               STATE = M3;
+                                                               break;
+                                                       }
+                                               }
+                                       }
+                               if (STATE == M3)
+                                       break;
+
+                               gu++;
+                               if (min > 2) {
+                                       STATE = M3;
+                                       break;
+                               }
+
+                               if ((rnd & 255) == 18)
+                                       if ((nodes & 1) > 0) {
+                                               c = m + 1;
+                                               c--;
+                                               while (Uc[c] > 0 || V[c] != 2)
+                                                       c--;
+                                               C[i] = c;
+                                       }
+
+                               if ((rnd & 255) == 17) {
+                                       c1 = (int) (MWC() & Mc[N]);
+                                       while (c1 >= m)
+                                               c1 = (int) (MWC() & Mc[N]);
+                                       c1++;
+
+                                       for (c = c1; c <= m; c++)
+                                               if (Uc[c] == 0)
+                                                       if (V[c] == 2) {
+                                                               C[i] = c;
+                                                               STATE = M3;
+                                                               break;
+                                                       }
+                                       for (c = 1; c < c1; c++)
+                                               if (Uc[c] == 0)
+                                                       if (V[c] == 2) {
+                                                               C[i] = c;
+                                                               STATE = M3;
+                                                               break;
+                                                       }
+                               }
+
+                       case M3:
+                               c = C[i];
+                               I[i]++;
+                               if (I[i] > Rows[c]) {
+                                       STATE = M44;
+                                       break;
+                               }
+
+                               r = Row[c][I[i]];
+                               if (Ur[r] > 0) {
+                                       STATE = M3;
+                                       break;
+                               }
+                               m0 = 0;
+                               m1 = 0;
+
+                               if (q > 0 && i > 32 && i < 65)
+                                       if ((MWC() & 127) < q) {
+                                               STATE = M3;
+                                               break;
+                                       }
+
+                               k = N4;
+                               x = (r - 1) / k + 1;
+                               y = ((r - 1) % k) / j + 1;
+                               s = (r - 1) % j + 1;
+
+                               if ((p & 1) > 0) {
+                                       j = N2;
+                                       k = N4;
+                                       x = (r - 1) / k + 1;
+                                       y = ((r - 1) % k) / j + 1;
+                                       s = (r - 1) % j + 1;
+                                       A[x - 1][y - 1] = s;
+                                       if (i == k) {
+                                               for (x = 0; x < j; x++)
+                                                       for (y = 0; y < j; y++)
+                                                               result = result.concat(String.valueOf(L[A[x][y]]));
+                                               result = result.concat(" #\n");
+                                       }
+                               }
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+                                       Uc[c1]++;
+                               }
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+
+                                       for (k = 1; k <= Rows[c1]; k++) {
+                                               r1 = Row[c1][k];
+                                               Ur[r1]++;
+                                               if (Ur[r1] == 1)
+                                                       for (l = 1; l <= Cols[r1]; l++) {
+                                                               c2 = Col[r1][l];
+                                                               V[c2]--;
+
+                                                               if (Uc[c2] + V[c2] < 1)
+                                                                       m0 = c2;
+                                                               if (Uc[c2] == 0 && V[c2] < 2)
+                                                                       m1 = c2;
+                                                       }
+                                       }
+                               }
+                               Node[i]++;
+                               tnodes++;
+                               nodes++;
+                               if (rnd > 99 && nodes > rnd) {
+                                       STATE = RESTART;
+                                       break;
+                               }
+                               if (i == N4)
+                                       solutions++;
+
+                               if (solutions >= smax) {
+                                       System.out.println("smax xolutions found");
+                                       if (_try_ == 1)
+                                               System.out.print("+");
+                                       STATE = NEXT_TRY;
+                                       break;
+                               }
+                               if (tnodes > vmax) {
+                                       if (_try_ == 1)
+                                               System.out.print("-");
+                                       STATE = NEXT_TRY;
+                                       break;
+                               }
+                               STATE = M22;
+                               break;
+
+                       case M44:
+                               i--;
+                               c = C[i];
+                               r = Row[c][I[i]];
+                               if (i == clues) {
+                                       STATE = NEXT_TRY;
+                                       break;
+                               }
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+                                       Uc[c1]--;
+
+                                       for (k = 1; k <= Rows[c1]; k++) {
+                                               r1 = Row[c1][k];
+                                               Ur[r1]--;
+
+                                               if (Ur[r1] == 0)
+                                                       for (l = 1; l <= Cols[r1]; l++) {
+                                                               c2 = Col[r1][l];
+                                                               V[c2]++;
+                                                       }
+                                       }
+                               }
+                               if (p > 0) {
+                                       j = N2;
+                                       k = N4;
+                                       x = (r - 1) / k + 1;
+                                       y = ((r - 1) % k) / j + 1;
+                                       s = (r - 1) % j + 1;
+                                       A[x - 1][y - 1] = 0;
+                               }
+                               if (i > clues) {
+                                       STATE = M3;
+                                       break;
+                               }
+
+                       case NEXT_TRY:
+                               time1 = System.currentTimeMillis();
+                               x1 = time1 - time0;
+
+                               time0 = time1;
+
+                               if (q > 0) {
+                                       xx = 128;
+                                       yy = 128 - q;
+                                       xx = xx / yy;
+                                       yy = solutions;
+                                       for (i = 1; i < 33; i++)
+                                               yy = yy * xx;
+                                       System.out.println("clues: " + clues + " estimated solutions:" + yy + " time " + x1 + "ms");
+
+                                       STATE = END;
+                                       break;
+                               }
+                               if ((p == 0 || p == 1) && tnodes <= 999999) {
+                                       if (solutions >= smax)
+                                               result = result.concat("More than " + solutions + " solutions ( bad sudoku!! ), rating "
+                                                               + (100 * tnodes / solutions) + ", time " + x1 + " ms");
+                                       else if (solutions == 1)
+                                               result = result.concat(solutions + " solution, rating " + (100 * tnodes) + ", time " + x1
+                                                               + " ms");
+                                       else if (solutions == 0)
+                                               result = result.concat("0 solutions, no rating possible, time " + x1 + " ms");
+                                       else
+                                               result = result.concat(solutions + " solutions ( bad sudoku!! ), rating "
+                                                               + (100 * tnodes / solutions) + ", time " + x1 + " ms");
+
+                                       STATE = END;
+                                       break;
+                               }
+                               if (p == 6) {
+                                       System.out.println(solutions);
+                                       STATE = END;
+                                       break;
+                               }
+                               if (p == 0 || p == 1) {
+                                       System.out.println(solutions + " solution(s), rating " + (100 * tnodes) + ", time " + x1 + "ms");
+                               }
+                               if (p > 5) {
+                                       x = 0;
+                                       for (i = 1; i <= N4; i++) {
+                                               x += Node[i];
+                                               System.out.print(Node[i]);
+                                               if (i % 9 == 0)
+                                                       System.out.println();
+                                       }
+                                       System.out.println(x);
+                               }
+                               STATE = END;
+                               break;
+                       } // end of switch statement
+               } // end of while loop
+               return result;
+       }
+
+       /**
+        * Helper function.
+        */
+       int shuffle() {
+               for (i = 1; i <= m; i++) {
+                       a = (int) ((MWC() >> 8) & Mc[N]);
+                       while (a >= i)
+                               a = (int) ((MWC() >> 8) & Mc[N]);
+                       a++;
+                       P[i] = P[a];
+                       P[a] = i;
+               }
+
+               for (c = 1; c <= m; c++) {
+                       Rows[c] = 0;
+                       T[c] = Uc[c];
+               }
+
+               for (c = 1; c <= m; c++)
+                       Uc[P[c]] = T[c];
+
+               for (r = 1; r <= n; r++)
+                       for (i = 1; i <= Cols[r]; i++) {
+                               c = P[Col[r][i]];
+                               Col[r][i] = c;
+                               Rows[c]++;
+                               Row[c][Rows[c]] = r;
+                       }
+
+               for (i = 1; i <= n; i++) {
+                       a = (int) ((MWC() >> 8) & Mr[N]);
+                       while (a >= i)
+                               a = (int) ((MWC() >> 8) & Mr[N]);
+                       a++;
+                       P[i] = P[a];
+                       P[a] = i;
+               }
+
+               for (r = 1; r <= n; r++) {
+                       Cols[r] = 0;
+                       T[r] = Ur[r];
+               }
+
+               for (r = 1; r <= n; r++)
+                       Ur[P[r]] = T[r];
+
+               for (c = 1; c <= m; c++)
+                       for (i = 1; i <= Rows[c]; i++) {
+                               r = P[Row[c][i]];
+                               Row[c][i] = r;
+                               Cols[r]++;
+                               Col[r][Cols[r]] = c;
+                       }
+
+               for (r = 1; r <= n; r++) {
+                       for (i = 1; i <= Cols[r]; i++) {
+                               a = (int) ((MWC() >> 8) & 7);
+                               while (a >= i)
+                                       a = (int) ((MWC() >> 8) & 7);
+                               a++;
+                               P[i] = P[a];
+                               P[a] = i;
+                       }
+
+                       for (i = 1; i <= Cols[r]; i++)
+                               T[i] = Col[r][P[i]];
+
+                       for (i = 1; i <= Cols[r]; i++)
+                               Col[r][i] = T[i];
+               }
+
+               for (c = 1; c <= m; c++) {
+                       for (i = 1; i <= Rows[c]; i++) {
+                               a = (int) ((MWC() >> 8) & Mw[N]);
+                               while (a >= i)
+                                       a = (int) ((MWC() >> 8) & Mw[N]);
+                               a++;
+                               P[i] = P[a];
+                               P[a] = i;
+                       }
+
+                       for (i = 1; i <= Rows[c]; i++)
+                               T[i] = Row[c][P[i]];
+
+                       for (i = 1; i <= Rows[c]; i++)
+                               Row[c][i] = T[i];
+               }
+               return 0;
+       }
+
+       private final Random random;
+
+       /** Creates a new instance of dlx_solver */
+       public dlx_solver(Random random) {
+               this.random = random;
+       }
+}
+
+/*******************************************************************************
+ * dlx_generator generate single solution locally minimized Sudoku puzzles.
+ * Locally minimized means that all keys that can be removed without creating a
+ * degenerate Sudoku (multiple solutions) are removed.
+ ******************************************************************************/
+class dlx_generator {
+       long MWC() {
+               return random.nextLong();
+       }
+
+       int Rows[] = new int[325], Cols[] = new int[730], Row[][] = new int[325][10], Col[][] = new int[730][5],
+                       Ur[] = new int[730], Uc[] = new int[325], V[] = new int[325], W[] = new int[325];
+       int P[] = new int[88], A[] = new int[88], C[] = new int[88], I[] = new int[88], Two[] = new int[888];
+       char B[] = { '0', '1', '1', '1', '2', '2', '2', '3', '3', '3', '1', '1', '1', '2', '2', '2', '3', '3', '3', '1',
+                       '1', '1', '2', '2', '2', '3', '3', '3', '4', '4', '4', '5', '5', '5', '6', '6', '6', '4', '4', '4', '5',
+                       '5', '5', '6', '6', '6', '4', '4', '4', '5', '5', '5', '6', '6', '6', '7', '7', '7', '8', '8', '8', '9',
+                       '9', '9', '7', '7', '7', '8', '8', '8', '9', '9', '9', '7', '7', '7', '8', '8', '8', '9', '9', '9' };
+       char H[][] = new char[326][7];
+       long c2, w;
+       int b, f, s1, m0, c1, r1, l, i1, m1, m2, a, p, i, j, k, r, c, d, n = 729, m = 324, x, y, s, z, fi;
+       int mi1, mi2, q7, part, nt, rate, nodes, solutions, min, samples, sam1, clues;
+       char L[] = { '.', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
+
+       /** State machine states */
+       static final int M0S = 10;
+       static final int M0 = 11;
+       static final int MR1 = 12;
+       static final int MR3 = 13;
+       static final int MR4 = 14;
+       static final int M2 = 15;
+       static final int M3 = 16;
+       static final int M4 = 17;
+       static final int M9 = 18;
+       static final int MR = 19;
+       static final int END = 20;
+       static final int M6 = 21;
+
+       /** Set to true to generate debug output */
+       boolean DBG = true;
+
+       /** Output trace messages */
+       void dbg(String s) {
+               if (DBG)
+                       System.out.println(s);
+       }
+
+       private final Random random;
+
+       public dlx_generator(Random random) {
+               dbg("In constructor");
+               this.random = random;
+       }
+
+       /**
+        * Save the generated Sudoku to a file.
+        */
+       void saveSudokuToFile(String s) {
+               FileOutputStream FO = null;
+               byte[] buffer = new byte[s.length() + 1];
+               int i = 0;
+
+               while (i < s.length()) {
+                       buffer[i] = (byte) s.charAt(i);
+                       i++;
+               }
+
+               try {
+                       FO = new FileOutputStream("generated_sudoku.sdk");
+                       FO.write(buffer);
+                       FO.close();
+               } catch (IOException IOE) {
+                       // Well, well, well....
+                       return;
+               }
+       }
+
+       /**
+        * Initialization code for both generate() and rate()
+        */
+       void initialize() {
+               for (i = 0; i < 888; i++) {
+                       j = 1;
+                       while (j <= i)
+                               j += j;
+                       Two[i] = j - 1;
+               }
+
+               r = 0;
+               for (x = 1; x <= 9; x++)
+                       for (y = 1; y <= 9; y++)
+                               for (s = 1; s <= 9; s++) {
+                                       r++;
+                                       Cols[r] = 4;
+                                       Col[r][1] = x * 9 - 9 + y;
+                                       Col[r][2] = (B[x * 9 - 9 + y] - 48) * 9 - 9 + s + 81;
+                                       Col[r][3] = x * 9 - 9 + s + 81 * 2;
+                                       Col[r][4] = y * 9 - 9 + s + 81 * 3;
+                               }
+
+               for (c = 1; c <= m; c++)
+                       Rows[c] = 0;
+
+               for (r = 1; r <= n; r++)
+                       for (c = 1; c <= Cols[r]; c++) {
+                               a = Col[r][c];
+                               Rows[a]++;
+                               Row[a][Rows[a]] = r;
+                       }
+
+               c = 0;
+               for (x = 1; x <= 9; x++)
+                       for (y = 1; y <= 9; y++) {
+                               c++;
+                               H[c][0] = 'r';
+                               H[c][1] = L[x];
+                               H[c][2] = 'c';
+                               H[c][3] = L[y];
+                               H[c][4] = 0;
+                       }
+
+               c = 81;
+               for (b = 1; b <= 9; b++)
+                       for (s = 1; s <= 9; s++) {
+                               c++;
+                               H[c][0] = 'b';
+                               H[c][1] = L[b];
+                               H[c][2] = 's';
+                               H[c][3] = L[s];
+                               H[c][4] = 0;
+                       }
+
+               c = 81 * 2;
+               for (x = 1; x <= 9; x++)
+                       for (s = 1; s <= 9; s++) {
+                               c++;
+                               H[c][0] = 'r';
+                               H[c][1] = L[x];
+                               H[c][2] = 's';
+                               H[c][3] = L[s];
+                               H[c][4] = 0;
+                       }
+
+               c = 81 * 3;
+               for (y = 1; y <= 9; y++)
+                       for (s = 1; s <= 9; s++) {
+                               c++;
+                               H[c][0] = 'c';
+                               H[c][1] = L[y];
+                               H[c][2] = 's';
+                               H[c][3] = L[s];
+                               H[c][4] = 0;
+                       }
+       }
+
+       /*
+        * Rating function
+        */
+       public long rate(String puzzle) {
+               int STATE = M6;
+               int Solutions;
+
+               z = 100;
+               fi = 0;
+               rate = 1;
+
+               for (i = 0; i < 88; i++)
+                       A[i] = 0;
+
+               initialize();
+
+               while (STATE != END) {
+                       switch (STATE) {
+                       case M6:
+                               clues = 0;
+                               for (i = 1; i <= 81; i++) {
+                                       c = puzzle.charAt(i - 1);
+                                       j = 0;
+
+                                       if (c == '-' || c == '.' || c == '0' || c == '*') {
+                                               A[i] = j;
+                                       } else {
+                                               while (L[j] != c && j <= 9)
+                                                       j++;
+
+                                               if (j <= 9) {
+                                                       A[i] = j;
+                                               }
+                                       }
+                               }
+
+                               if (clues == 81) {
+                                       clues--;
+                                       A[1] = 0;
+                               }
+
+                               nt = 0;
+                               mi1 = 9999;
+                               for (f = 0; f < z; f++) {
+                                       Solutions = solve();
+                                       if (Solutions != 1) {
+                                               if (Solutions > 1)
+                                                       nt = -1 * Solutions;
+                                               STATE = END;
+                                               break;
+                                       }
+                                       nt += nodes;
+                                       if (nodes < mi1) {
+                                               mi1 = nodes;
+                                               mi2 = C[clues];
+                                       }
+                               }
+                               if (STATE == END)
+                                       break;
+
+                               if (fi > 0)
+                                       if ((nt / z) > fi) {
+                                               for (i = 1; i <= 81; i++)
+                                                       System.out.println(L[A[i]]);
+                                               System.out.println();
+                                               STATE = M6;
+                                               break;
+                                       }
+
+                               if (fi > 0) {
+                                       STATE = M6;
+                                       break;
+                               }
+
+                               if ((z & 1) > 0) {
+                                       System.out.println(nt / z);
+                                       STATE = M6;
+                                       break;
+                               }
+
+                               if (rate > 1)
+                                       System.out.println("hint: " + H[mi2]);
+
+                               STATE = END;
+                               break;
+                       } // End of switch statement
+               } // End of while loop
+               return (nt);
+       }
+
+       public String[] generate(int Samples, int Rate) {
+               int STATE = M0S;
+               String result[] = new String[Samples];
+
+               dbg("Entering generate");
+
+               samples = 1000;
+               if (Samples > 0)
+                       samples = Samples;
+
+               for (i = 0; i < samples; i++)
+                       result[i] = new String();
+
+               // Set to 1 for rating, set to 2 for rating and hint
+               rate = 0;
+               if (Rate > 0)
+                       rate = Rate;
+               if (rate > 2)
+                       rate = 2;
+
+               initialize();
+
+               dbg("Entering state machine");
+
+               sam1 = -1;
+               while (STATE != END) {
+                       switch (STATE) {
+                       case M0S:
+                               sam1++;
+                               if (sam1 >= samples) {
+                                       STATE = END;
+                                       break;
+                               }
+
+                       case M0:
+                               for (i = 1; i <= 81; i++)
+                                       A[i] = 0;
+                               part = 0;
+                               q7 = 0;
+
+                       case MR1:
+                               i1 = (int) ((MWC() >> 8) & 127);
+                               if (i1 > 80) {
+                                       STATE = MR1;
+                                       break;
+                               }
+
+                               i1++;
+                               if (A[i1] > 0) {
+                                       STATE = MR1;
+                                       break;
+                               }
+
+                       case MR3:
+                               s = (int) ((MWC() >> 9) & 15);
+                               if (s > 8) {
+                                       STATE = MR3;
+                                       break;
+                               }
+
+                               s++;
+                               A[i1] = s;
+                               m2 = solve();
+                               q7++;
+
+                               if (m2 < 1)
+                                       A[i1] = 0;
+
+                               if (m2 != 1) {
+                                       STATE = MR1;
+                                       break;
+                               }
+
+                               part++;
+                               if (solve() != 1) {
+                                       STATE = M0;
+                                       break;
+                               }
+
+                       case MR4:
+                               for (i = 1; i <= 81; i++) {
+                                       x = (int) ((MWC() >> 8) & 127);
+                                       while (x >= i) {
+                                               x = (int) ((MWC() >> 8) & 127);
+                                       }
+                                       x++;
+                                       P[i] = P[x];
+                                       P[x] = i;
+                               }
+
+                               for (i1 = 1; i1 <= 81; i1++) {
+                                       s1 = A[P[i1]];
+                                       A[P[i1]] = 0;
+                                       if (solve() > 1)
+                                               A[P[i1]] = s1;
+                               }
+
+                               if (rate > 0) {
+                                       nt = 0;
+                                       mi1 = 9999;
+                                       for (f = 0; f < 100; f++) {
+                                               solve();
+                                               nt += nodes;
+                                               if (nodes < mi1) {
+                                                       mi1 = nodes;
+                                                       mi2 = C[clues];
+                                               }
+                                       }
+                                       result[sam1] = result[sam1].concat("Rating:" + nt + "# ");
+                                       if (rate > 1) {
+                                               result[sam1] = result[sam1].concat("hint: " + String.valueOf(H[mi2]).substring(0, 4) + " #\n");
+                                       } else
+                                               result[sam1] = result[sam1].concat("\n");
+                               }
+
+                               for (i = 1; i <= 81; i++) {
+                                       result[sam1] = result[sam1].concat(String.valueOf(L[A[i]]));
+                                       if (i % 9 == 0) {
+                                               result[sam1] = result[sam1].concat("\n");
+                                       }
+                               }
+                               result[sam1] = result[sam1].concat("\n");
+
+                       default:
+                               dbg("Default case. New state M0S");
+                               STATE = M0S;
+                               break;
+                       } // end of switch statement
+               } // end of while loop
+               return result;
+       }
+
+       int solve() {
+               // returns 0 (no solution), 1 (unique sol.), 2 (more than
+                                       // one sol.)
+               int STATE = M2;
+
+               for (i = 0; i <= n; i++)
+                       Ur[i] = 0;
+               for (i = 0; i <= m; i++)
+                       Uc[i] = 0;
+               clues = 0;
+
+               for (i = 1; i <= 81; i++)
+                       if (A[i] > 0) {
+                               clues++;
+                               r = i * 9 - 9 + A[i];
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       d = Col[r][j];
+                                       if (Uc[d] > 0)
+                                               return 0;
+                                       Uc[d]++;
+
+                                       for (k = 1; k <= Rows[d]; k++) {
+                                               Ur[Row[d][k]]++;
+                                       }
+                               }
+                       }
+
+               for (c = 1; c <= m; c++) {
+                       V[c] = 0;
+                       for (r = 1; r <= Rows[c]; r++)
+                               if (Ur[Row[c][r]] == 0)
+                                       V[c]++;
+               }
+
+               i = clues;
+               m0 = 0;
+               m1 = 0;
+               solutions = 0;
+               nodes = 0;
+
+               dbg("Solve: Entering state machine");
+
+               while (STATE != END) {
+                       switch (STATE) {
+                       case M2:
+                               i++;
+                               I[i] = 0;
+                               min = n + 1;
+                               if ((i > 81) || (m0 > 0)) {
+                                       STATE = M4;
+                                       break;
+                               }
+
+                               if (m1 > 0) {
+                                       C[i] = m1;
+                                       STATE = M3;
+                                       break;
+                               }
+
+                               w = 0;
+                               for (c = 1; c <= m; c++)
+                                       if (Uc[c] == 0) {
+                                               if (V[c] < 2) {
+                                                       C[i] = c;
+                                                       STATE = M3;
+                                                       break;
+                                               }
+
+                                               if (V[c] <= min) {
+                                                       w++;
+                                                       W[(int) w] = c;
+                                               }
+                                               ;
+
+                                               if (V[c] < min) {
+                                                       w = 1;
+                                                       W[(int) w] = c;
+                                                       min = V[c];
+                                               }
+                                       }
+
+                               if (STATE == M3) {
+                                       // break in for loop detected, continue breaking
+                                       break;
+                               }
+
+                       case MR:
+                               c2 = (MWC() & Two[(int) w]);
+                               while (c2 >= w) {
+                                       c2 = (MWC() & Two[(int) w]);
+                               }
+                               C[i] = W[(int) c2 + 1];
+
+                       case M3:
+                               c = C[i];
+                               I[i]++;
+                               if (I[i] > Rows[c]) {
+                                       STATE = M4;
+                                       break;
+                               }
+
+                               r = Row[c][I[i]];
+                               if (Ur[r] > 0) {
+                                       STATE = M3;
+                                       break;
+                               }
+                               m0 = 0;
+                               m1 = 0;
+                               nodes++;
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+                                       Uc[c1]++;
+                               }
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+                                       for (k = 1; k <= Rows[c1]; k++) {
+                                               r1 = Row[c1][k];
+                                               Ur[r1]++;
+                                               if (Ur[r1] == 1)
+                                                       for (l = 1; l <= Cols[r1]; l++) {
+                                                               c2 = Col[r1][l];
+                                                               V[(int) c2]--;
+                                                               if (Uc[(int) c2] + V[(int) c2] < 1)
+                                                                       m0 = (int) c2;
+                                                               if (Uc[(int) c2] == 0 && V[(int) c2] < 2)
+                                                                       m1 = (int) c2;
+                                                       }
+                                       }
+                               }
+
+                               if (i == 81)
+                                       solutions++;
+
+                               if (solutions > 1) {
+                                       STATE = M9;
+                                       break;
+                               }
+                               STATE = M2;
+                               break;
+
+                       case M4:
+                               i--;
+                               if (i == clues) {
+                                       STATE = M9;
+                                       break;
+                               }
+                               c = C[i];
+                               r = Row[c][I[i]];
+
+                               for (j = 1; j <= Cols[r]; j++) {
+                                       c1 = Col[r][j];
+                                       Uc[c1]--;
+                                       for (k = 1; k <= Rows[c1]; k++) {
+                                               r1 = Row[c1][k];
+                                               Ur[r1]--;
+                                               if (Ur[r1] == 0)
+                                                       for (l = 1; l <= Cols[r1]; l++) {
+                                                               c2 = Col[r1][l];
+                                                               V[(int) c2]++;
+                                                       }
+                                       }
+                               }
+
+                               if (i > clues) {
+                                       STATE = M3;
+                                       break;
+                               }
+
+                       case M9:
+                               STATE = END;
+                               break;
+                       default:
+                               STATE = END;
+                               break;
+                       } // end of switch statement
+               } // end of while statement
+               return solutions;
+       }
+}
+
+/**
+ * 
+ * @author Rolf Sandberg
+ */
+
+class xxxDLXEngine {
+       dlx_generator generator;
+       dlx_solver solver;
+
+       public xxxDLXEngine(Random random) {
+               generator = new dlx_generator(random);
+               solver = new dlx_solver(random);
+       }
+
+       String generate(int minrating, int maxrating) {
+               // Date t = new Date();
+               // long start = t.getTime();
+               // int tries = 0, i, samples = 5;
+               // long rating = 0;
+               String ss[] = generator.generate(1, 0);
+               return ss[0];
+
+               // Generator:
+               // First arg: rand seed
+               // Second arg: #samples, ignored if <= 0
+               // Third arg: rating and hints, ignored if <= 0
+
+               // Task: Find a Sudoku with a rating in a specified interval.
+               // Do it by generating samples and examine them
+               // Continue until an appropriate puzzle is found.
+               // while(tries < 9999999) {
+               // tries++;
+               // t = new Date();
+               // ss = generator.generate(samples, 0);
+               // for(i = 0; i < samples; i++) {
+               // rating = generator.rate(ss[i].replace("\n","").trim());
+               // if(rating > minrating && rating < maxrating) {
+               // return ss[i];
+               // }
+               // }
+               // System.out.println(minrating + ", " + maxrating + ", " + rating + ",
+               // looping");
+               // }
+               // return ss[0];
+       }
+
+       long rate(String s) {
+               return generator.rate(s);
+       }
+
+       String solve(String s) {
+               String result = solver.solve(s);
+               return result;
+       }
+}      
+
+public class DLXEngine {
+       dlx_generator generator;
+       dlx_solver solver;
+
+       public DLXEngine(Random random) {
+               generator = new dlx_generator(random);
+               solver = new dlx_solver(random);
+       }
+
+       public String generate(int minrating, int maxrating){
+               int tries = 0, i, samples = 5;
+               long rating = 0;
+               String ss[] = new String[samples];
+
+               for(tries = 0; tries < samples; tries++)
+                       ss[tries] = new String();
+               tries = 1;
+
+               // Generator:
+                       // First arg: rand seed
+                       // Second arg: #samples, ignored if <= 0
+               // Third arg: rating and hints, ignored if <= 0
+
+               // Task: Find a Sudoku with a rating in a specified interval.
+               // Do it by generating samples and examine them
+               // Continue until an appropriate puzzle is found.
+               while(tries < 9999999) {
+                       tries++;
+                       ss = generator.generate(samples, 0);
+                       for(i = 0; i < samples; i++) {
+                               rating = generator.rate(ss[i].replace("\n","").trim());
+                               if(rating > minrating && rating < maxrating) {
+                                       System.out.println(minrating + ", " + maxrating + ", " + rating);
+                                       return ss[i];
+                               }
+                       }
+               }
+               return ss[0];
+       }
+
+       public long rate(String s) {
+               return generator.rate(s);
+       }
+
+       public String solve(String s){
+               String result = solver.solve(s);
+               return result;
+       }
+}