58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
/*
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* Copyright (C) 2022 Camden Dixie O'Brien
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public
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* License along with this program. If not, see
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* <https://www.gnu.org/licenses/>.
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*/
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#include "solve.h"
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#include <stdio.h>
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int solve(struct sudoku *sud)
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{
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unsigned r, c, n, val, np, pr, pc;
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bool match;
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for (n = 0;; ++n) {
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match = false;
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/* Check if only one place a value can go on each row. */
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for (r = 0; r < NDIGITS; ++r) {
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for (val = 0; val < NDIGITS; ++val) {
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np = 0;
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for (c = 0; c < NDIGITS; ++c) {
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if (!sud->cells[r][c].det && sud->cells[r][c].pvals[val]) {
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pr = r;
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pc = c;
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++np;
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if (np > 1)
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break;
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}
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}
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if (np == 1) {
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if (update(sud, pr, pc, val) != OK)
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return -1;
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match = true;
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}
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}
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}
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/* Exit if no matches. */
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if (!match)
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return n;
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}
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}
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