git.itanic.dy.fi Git - sudoku/blob - sudoku.cpp

   1 #include <iostream>
   2 #include <string>
   3
   4 #include "sudoku.h"
   5 #include "debug.h"
   6 #include "random.h"
   7
   8 #define EMPTY ' '
   9
  10 int verbose = 1;
  11
  12 sudoku::sudoku()
  13 {
  14         int x,y;
  15
  16         for (y = 0; y < 9; y++)
  17                 for (x = 0; x < 9; x++)
  18                         table[x][y] = EMPTY;
  19
  20         recursion_depth = 0;
  21         guesses = 0;
  22 }
  23
  24 sudoku::~sudoku()
  25 {
  26 }
  27
  28 static int check_validity(const int col, const int row)
  29 {
  30         if (col < 0 || col >= 9) {
  31                 DPRINT << "Invalid column: " << col << std::endl;
  32                 return 0;
  33         }
  34
  35         if (row < 0 || row >= 9) {
  36                 DPRINT << "Invalid row: " << row << std::endl;
  37                 return 0;
  38         }
  39         return 1;
  40 }
  41
  42 char sudoku::get(const int col, const int row)
  43 {
  44         if (!check_validity(row, col)) {
  45                 DPRINT << "over here\n";
  46                 return 0;
  47         }
  48
  49         return table[col][row];
  50 }
  51
  52 int sudoku::set(const int col, const int row, const char val)
  53 {
  54         std::string str;
  55
  56         if (!check_validity(col, row)) {
  57                 DPRINT << "over here\n";
  58                 return -1;
  59         }
  60
  61         if (table[col][row] != EMPTY) {
  62                 DPRINT << "Assigning value to a non-empty slot\n";
  63                 return -1;
  64         }
  65
  66         str = get_col_contents(col);
  67         if (str.find(val, 0) != std::string::npos) {
  68                 DPRINT << "Illegal assignment " << col << "." << row << ": "
  69                        << val << std::endl;
  70                 return -1;
  71         }
  72
  73         str = get_row_contents(row);
  74         if (str.find(val, 0) != std::string::npos) {
  75                 DPRINT << "Illegal assignment " << col << "." << row << ": "
  76                        << val << std::endl;
  77                 return -1;
  78         }
  79
  80         str = get_block_contents(col, row);
  81         if (str.find(val, 0) != std::string::npos) {
  82                 DPRINT << "Illegal assignment " << col << "." << row << ": "
  83                        << val << std::endl;
  84                 return -1;
  85         }
  86
  87         table[col][row] = val;
  88
  89         return 0;
  90 }
  91
  92 int sudoku::str_to_row(const int row, const std::string &str)
  93 {
  94         unsigned int i, col = 0;
  95         char chr;
  96
  97         if (row < 0 || row >= 9) {
  98                 DPRINT << "Illegal row " << row << std::endl;
  99                 return -1;
 100         }
 101
 102         for (i = 0; i < str.length(); i++) {
 103                 chr = str.at(i);
 104
 105                 if ((chr == '?') ||
 106                     (chr == '_') ||
 107                     (chr == '.')){
 108                         col++;
 109                         continue;
 110                 }
 111
 112                 /* Ignore non-numbers */
 113                 if (chr < '1' || chr > '9')
 114                         continue;
 115
 116                 set(col++, row, chr);
 117                 if (col >= 9)
 118                         break;
 119         }
 120         return 0;
 121 }
 122
 123 void sudoku::print(void)
 124 {
 125         int x, y;
 126
 127         printf("+-------+------+--------+\n");
 128         for (y = 0; y < 9; y++) {
 129                 printf("| ");
 130                 for (x = 0; x < 9; x++) {
 131                         printf("%c ", table[x][y]);
 132                         if (!((x  + 1)% 3))
 133                                 printf("| ");
 134                 }
 135                 printf("\n");
 136                 if (!((y + 1) % 3))
 137                         printf("+-------+-------+-------+\n");
 138         }
 139 }
 140
 141 void sudoku::print_compact(void)
 142 {
 143         int x, y, i = 0;
 144         char str[82];
 145         str[81] = 0;
 146
 147         for (y = 0; y < 9; y++)
 148                 for (x = 0; x < 9; x++, i++)
 149                         str[i] = table[x][y] != EMPTY ? table[x][y] : '.';
 150
 151         printf("%s\n", str);
 152 }
 153
 154 void sudoku::clone_to(sudoku &to)
 155 {
 156         sudoku clone;
 157         int x, y;
 158
 159         for (x = 0; x < 9; x++)
 160                 for (y = 0; y < 9; y++)
 161                         to.table[x][y] = table[x][y];
 162 }
 163
 164 std::string sudoku::get_row_contents(int row)
 165 {
 166         std::string s;
 167         int col;
 168
 169         for (col = 0; col < 9; col++) {
 170                 if (table[col][row] != EMPTY)
 171                         s += table[col][row];
 172         }
 173
 174         return s;
 175 }
 176
 177 std::string sudoku::get_col_contents(int col)
 178 {
 179         std::string s;
 180         int row;
 181
 182         for (row = 0; row < 9; row++) {
 183                 if (table[col][row] != EMPTY)
 184                         s += table[col][row];
 185         }
 186
 187         return s;
 188 }
 189
 190 std::string sudoku::get_block_contents(int col, int row)
 191 {
 192         std::string s;
 193         int x, y;
 194         char c;
 195
 196         if (col < 0 || col >= 9)
 197                 DPRINT "Aiee " << col << std::endl;
 198         if (row < 0 || row >= 9)
 199                 DPRINT "Aiee " << row << std::endl;
 200
 201         col = (col /= 3) * 3;
 202         row = (row /= 3) * 3;
 203
 204         for (y = 0; y < 3; y++)
 205                 for (x = 0; x < 3; x++) {
 206                         c = get(x + col, y + row);
 207                         if (c != EMPTY)
 208                                 s += c;
 209                 }
 210
 211         return s;
 212 }
 213
 214 static std::string exclude_common(std::string s1, std::string s2)
 215 {
 216         std::string::iterator a, b;
 217
 218 restart:
 219         for (a = s1.begin(); a != s1.end(); a++) {
 220                 for (b = s2.begin(); b != s2.end(); b++) {
 221                         if (*a == *b) {
 222                                 a = s1.erase(a);
 223                                 b = s2.erase(b);
 224                                 goto restart;
 225                         }
 226                 }
 227         }
 228         return s1;
 229 }
 230
 231 std::string sudoku::get_legal_numbers(int col, int row)
 232 {
 233         char val;
 234         std::string a, b, c, ret;
 235
 236         if (!check_validity(col, row)) {
 237                 DPRINT << "over here\n";
 238                 return NULL;
 239         }
 240
 241         val = get(col, row);
 242         if (val != EMPTY) {
 243                 return "0";
 244         }
 245
 246 //      std::cout << "[" << col << "." << row << "] ";
 247
 248         a = get_col_contents(col);
 249 //      std::cout << " col " << a;
 250
 251         b = get_row_contents(row);
 252 //      std::cout << " row " << b;
 253
 254         c = get_block_contents(col, row);
 255 //      std::cout << " block " << c;
 256
 257         ret = exclude_common("123456789", a);
 258         ret = exclude_common(ret, b);
 259         ret = exclude_common(ret, c);
 260
 261 //      std::cout << " legal " << ret << std::endl;
 262         return ret;
 263 }
 264
 265 int sudoku::fill_missing()
 266 {
 267         int x, y, solved = 0;
 268         std::string num;
 269
 270         for (y = 0; y < 9; y++)
 271                 for (x = 0; x < 9; x++) {
 272                                 num = get_legal_numbers(x, y);
 273                                 if ((num != "0") && (num.length() == 1)) {
 274                                         set(x, y, num[0]);
 275                                         solved++;
 276                         }
 277                 }
 278         if (verbose) {
 279                 //std::cout << "Solved " << solved << " numbers\n";
 280         }
 281
 282         return solved;
 283 }
 284
 285 int sudoku::get_best_guess(int &col, int &row)
 286 {
 287         int x, y;
 288         int min = 0, filled = 0, illegals = 0;
 289         std::string numbers;
 290
 291         /*
 292          * Initialize row and col with illegal values to spot possible
 293          * misuse
 294          */
 295         col = -1;
 296         row = -1;
 297
 298         for (y = 0; (y < 9) && !illegals; y++)
 299                 for (x = 0; x < 9; x++) {
 300                         numbers = get_legal_numbers(x, y);
 301
 302                         if (numbers == "0") {
 303                                 filled++;
 304                                 continue;
 305                         }
 306
 307                         if (numbers.length() == 0) {
 308                                 illegals++;
 309                                 break;
 310                         }
 311
 312                         if (!min) {
 313                                 min = numbers.length();
 314                                 col = x;
 315                                 row = y;
 316                                 continue;
 317                         }
 318
 319                         if ((int)numbers.length() < min) {
 320                                 min = numbers.length();
 321                                 col = x;
 322                                 row = y;
 323                                 if (min == 1)
 324                                         return min;
 325                         }
 326 //                      std::cout <<  x << "." << y << ": " << " min "
 327 //                                << numbers << col << "." << row << std::endl;
 328                 }
 329
 330         if ((!min && !filled) || illegals) {
 331 //              DPRINT << "Is this sudoku has no solutions?\n";
 332                 return -1;
 333         }
 334
 335         if (!min && (filled == 99)) {
 336                 DPRINT << "This sudoku is solved\n";
 337                 return 0;
 338         }
 339
 340         return min;
 341 }
 342
 343 std::vector<sudoku> sudoku::solve_all()
 344 {
 345         int x, y, i, j, ret;
 346         std::string str;
 347         std::vector<sudoku> sudokus;
 348
 349         // Fill in as much as possible
 350         do {
 351                 if (verbose) {
 352                         std::cout << std::endl;
 353                         print();
 354                 }
 355         } while (fill_missing() != 0);
 356
 357         ret = get_best_guess(x, y);
 358
 359         // Did we solve it yet?
 360         switch (ret) {
 361         case -1:
 362                 // Unsolvable
 363                 if (verbose) {
 364                         std::cout << "This is unsolvable, recursion: "
 365                                   << recursion_depth << std::endl;
 366                 }
 367                 return sudokus;
 368         case 0:
 369                 // Solved
 370                 if (verbose) {
 371                         std::cout << "Solution found , recursion: "
 372                                   << recursion_depth << std::endl;
 373                 }
 374                 sudokus.push_back(*this);
 375                 if (verbose)
 376                         print();
 377                 return sudokus;
 378         }
 379
 380         if (verbose) {
 381                 std::cout << "Not solved yet, guessing at depth "
 382                           << recursion_depth << std::endl;
 383         }
 384
 385         // Try guessim something
 386         str = get_legal_numbers(x, y);
 387         for (i = 0; i < (int)str.length(); i++) {
 388                 std::vector<sudoku> results;
 389
 390                 sudoku guess = *this;
 391                 guesses++;
 392
 393                 if (verbose) {
 394                         std::cout << "Guessing number " << str[i] << " to "
 395                                   << x << "." << y << std::endl;
 396                 }
 397
 398                 guess.set(x, y, str[i]);
 399                 guess.recursion_depth = recursion_depth + 1;
 400                 guess.guesses = 0;
 401
 402                 results = guess.solve_all();
 403                 guesses += guess.guesses;
 404
 405                 //Did it solve?
 406                 if (!results.empty()) {
 407 /*                      printf("Got %d solutions, guessed %d: %s\n",
 408                                (int)results.size(), (int)str.size(),
 409                                str.c_str());*/
 410
 411                         for(j = 0;j < (int)results.size(); j++) {
 412                                 sudokus.push_back(results.at(j));
 413                                 guesses += results.at(j).guesses;
 414                         }
 415                 }
 416         }
 417
 418         if (verbose)
 419                 std::cout << "Guesses: " << guesses << std::endl;
 420
 421         // Return what was solved
 422         return sudokus;
 423 }
 424
 425 sudoku sudoku::fill_with_random(int &solvable)
 426 {
 427         int x, y, i, ret;
 428         std::string str;
 429         sudoku empty;
 430
 431         // Fill in as much as possible
 432         do {
 433                 if (verbose) {
 434                         //std::cout << std::endl;
 435                         //print();
 436                 }
 437         } while (fill_missing() != 0);
 438
 439         ret = get_best_guess(x, y);
 440
 441         // Did we fill it yet?
 442         switch (ret) {
 443         case -1:
 444                 // Unsolvable
 445                 solvable = 0;
 446                 if (verbose) {
 447                         //std::cout << "This is unsolvable, recursion: "
 448                         //  << recursion_depth << std::endl;
 449                 }
 450                 return empty;
 451         case 0:
 452                 // Solved
 453                 solvable = 1;
 454                 if (verbose) {
 455                         //std::cout << "Solution found , recursion: "
 456                         //  << recursion_depth << std::endl;
 457                 }
 458                 return *this;
 459         }
 460
 461         if (verbose) {
 462                 //std::cout << "Not solved yet, guessing at depth "
 463                 //  << recursion_depth << std::endl;
 464         }
 465
 466         // Try filling with something
 467         str = get_legal_numbers(x, y);
 468         while (str.length()) {
 469                 i = get_random() % str.length();
 470
 471                 sudoku guess = *this;
 472                 guess.set(x, y, str[i]);
 473
 474                 if (verbose) {
 475                         //std::cout << "Trying number " << str[i] << " to "
 476                         //  << x << "." << y << std::endl;
 477                 }
 478
 479                 guess.recursion_depth = recursion_depth + 1;
 480
 481                 int can_solve;
 482                 guess = guess.fill_with_random(can_solve);
 483
 484                 //Did it solve?
 485                 if (can_solve) {
 486                         solvable = 1;
 487                         return guess;
 488                 }
 489
 490                 str.erase(i,1);
 491         }
 492
 493         // It didn't solve
 494         solvable = 0;
 495         return empty;
 496 }
 497
 498 int sudoku::used_numbers()
 499 {
 500         int x, y, count = 0;
 501         for (x = 0; x < 9; x++)
 502                 for (y = 0; y < 9; y++)
 503                         if (table[x][y] != EMPTY)
 504                                 count++;
 505         return count;
 506 }
 507
 508 static int done = 0;
 509
 510 sudoku sudoku::remove_randomly(int min_guesses, int depth)
 511 {
 512         int count = used_numbers();
 513         sudoku result;
 514         int stop = 0;
 515
 516 #pragma omp parallel for firstprivate(stop)
 517         for (int i = 0; i < count; i++) {
 518                 int x, y;
 519                 sudoku tmp = *this, tmp2;
 520                 std::vector<sudoku> results;
 521
 522                 if (done || stop)
 523                         continue;
 524
 525                 /* remove a number */
 526                 do {
 527                         x = get_random() % 9;
 528                         y = get_random() % 9;
 529                 } while(tmp.get(x,y) == EMPTY);
 530                 tmp.table[x][y] = EMPTY;
 531
 532                 //printf("Got now:\n");
 533                 //tmp.print();
 534
 535                 tmp2 = tmp;
 536                 /* solve it */
 537                 results = tmp.solve_all();
 538
 539                 /* Does it still have only one solution */
 540                 if (results.size() == 1 && !done) {
 541                         /* but not hard enough yet? */
 542                         if (tmp.guesses >= min_guesses) {
 543                                 /* It's good now */
 544                                 printf("%d, Good!\n", depth);
 545                                 result = tmp;
 546                                 done = 1;
 547                                 #pragma omp flush(done)
 548                         } else {
 549                                 printf("%2d, got only %3d guesses ", depth,
 550                                        tmp.guesses);
 551                                 tmp.print_compact();
 552                         }
 553
 554                         if (!done) {
 555                                 tmp = tmp2;
 556                                 tmp2 = tmp.remove_randomly(min_guesses,
 557                                                    depth + 1);
 558
 559                                 /* test for emptiness */
 560                                 if (tmp2.guesses == 0) {
 561                                         continue;
 562                                 }
 563
 564                                 if (tmp2.guesses >= min_guesses) {
 565                                         result = tmp2;
 566                                         done = 1;
 567                                         #pragma omp flush(done)
 568                                 } else {
 569                                         printf("%d: Guesses: %d, "
 570                                                "not good enough\n",
 571                                                depth, tmp2.guesses);
 572                                 }
 573                                 continue;
 574                         }
 575                 }
 576
 577                 if ((results.size() > 1) && !done) {
 578                         /* oops, removed too many */
 579                         sudoku empty;
 580                         //printf("%d, Got multiple results\n", depth);
 581                         result = empty;
 582                         stop = 1;
 583                 }
 584
 585                 if (results.empty() && !done) {
 586                         fprintf(stderr, "%d, Fail. This can't happen?\n",
 587                                 depth);
 588                         sudoku empty;
 589                         result = empty;
 590                 }
 591         }
 592         return result;
 593 }
 594
 595 int sudoku::generate(int min_guesses)
 596 {
 597         int solvable;
 598         sudoku tmp = fill_with_random(solvable);
 599
 600         if (!solvable)
 601                 return -1;
 602
 603         /* Right, we got it filled */
 604         tmp = tmp.remove_randomly(min_guesses, 0);
 605
 606         *this = tmp;
 607
 608         return solvable;
 609 }