summaryrefslogtreecommitdiff
path: root/solve.c
blob: 7aae70762471b60ace440dc24881a5fdf4b2bbd9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
#include <stdio.h>
#include <string.h>

#include "debug.h"
#include "update.h"
#include "cell.h"
#include "display.h"
#include "load.h"

/*
 * For all unsolved cells on the board, solve them if they have been marked as
 * impossible to be 8/9 values
 */
int solve_row_col(struct cell (*b)[9][9])
{
	int change_count = 0;
	int x = 0;
	int y = 0;
	int i = 0;
	int val = 0;
	int total = 0;

	for (y = 0; y < 9; y++)
	{
		total = 0;
		for (x = 0; x < 9; x++)
		{
			if ((*b)[x][y].val != 0)
				continue;

			for (i = 0; i < 9; i++)
			{
				if (CELL_IS_NOT((*b)[x][y].not, val))
				{
					total++;
				} else {
					val = i;
				}
			}
			if (total == 8) {
				printf("%c%c must be %d because it is the only missing value in its row or column\n", NAME_CELL(x,y), val);
				DEBUG_LOG("ROW/COL: (%d,%d) must be %d\n", x, y, val);
				(*b)[x][y].val = val;
				change_count++;
			}
		}
	}
	return change_count;
}


/*
 * FIXME rename - cell != cell
 * For all unsolved cells on the board, solve them if they are the only place
 * left in their local 3x3 (box) that a value missing from that box could fit
 */
int not_to_val_cell(struct cell (*b)[9][9])
{
	int change_count = 0;
	int bx = 0;
	int by = 0;
	int x = 0;
	int y = 0;
	int n = 0;
	int potentials = 0;
	int okx, oky;
	struct cell *c;

	/* refactor this crap */
	for (by = 0; by < 9; by += 3)
	{
		for (bx = 0; bx < 9; bx += 3)
		{
			/* for each val that has to be in cell */
			for (n = 1; n <= 9; n++)
			{
				for (y = 0; y < 3; y++)
				{
					for (x = 0; x < 3; x++)
					{
						c = &(*b)[bx+x][by+y];
						if (c->val == n)
						{
							potentials = 0;
							y = 3;
							break;
						}
						if (c->val)
							continue;

						if (!CELL_IS_NOT(c->not, n))
						{
							potentials++;
							okx = x;
							oky = y;
						}
					}
				}
				if (potentials == 1)
				{
					DEBUG_LOG("CELL: (%d,%d) must be %d\n", bx + okx, by + oky, n);
					printf("%c%c must be %d because it can't be anything else\n",
						NAME_CELL(bx+okx, by+oky), n);
					(*b)[bx+okx][by+oky].val = n;
					potentials = 0;
					change_count++;
				}
			}
		}
	}
	return change_count;
}


/* For the numbers 1-9 not filled into a cell, fill in those which have only
 * one place they can go */
int cell_fill_certainties(struct cell (*b)[9][9], int bx, int by)
{
	int change_count = 0;
	int will_take_count = 0;
	int will_take_x = 0;
	int will_take_y = 0;
	int val = 0;
	int cell_has = 0;
	int x,y;

	/* Translate cell-based index to tile-based */
	bx *= 3;
	by *= 3;

	/* First: walk the cell and find which values it has */
	for (x = bx; x < bx + 3; x++) {
		for (y = by; y < by + 3; y++) {
			val = (*b)[x][y].val;
			if (val) {
				DEBUG_LOG("CELL_CERT: Cell (%d,%d) has %d\n", bx/3, by/3, val);
				cell_has |= CELL_VALUE_MASK(val);
			}
		}
	}

	/* Second: For all missing values, see if only one tile will take it.
	 * If only one will have it, put it in */
	for (val = 1; val <= 9; val++) {

		will_take_count = 0;

		/* Does the cell lack the value? */
		if (!(cell_has & CELL_VALUE_MASK(val))) {

			DEBUG_LOG("Try to solve for %d\n", val);

			/* Walk the cell and find which tile(s) will take it */
			for (x = bx; x < bx + 3; x++) {
				for (y = by; y < by + 3; y++) {
					if ((*b)[x][y].val) {
						continue;
					}
					if (!CELL_IS_NOT((*b)[x][y].not, val)) {
						will_take_count++;
						will_take_x = x;
						will_take_y = y;
					}
				}
			}
			DEBUG_LOG("will_take_count is %d\n", will_take_count);
			/* Don't make indeterminate choices here*/
			if (will_take_count == 1) {
				printf("%c%c must be %d because it is the only place in its box this will fit\n",
					NAME_CELL(will_take_x, will_take_y),
					val);
				(*b)[will_take_x][will_take_y].val = val;
				change_count++;
			}
		}
	}
	return change_count;
}

int cells_fill_certainties(struct cell (*b)[9][9])
{
	int change_count = 0;
	int x, y;

	for (x = 0; x < 3; x++) {
		for (y = 0; y < 3; y++) {
			change_count += cell_fill_certainties(b, x, y);
		}
	}
	return change_count;
}

/*
 * Check if every cell on a board is filled.
 * Returns -1 isf the board is not fully
 * Returns 0 if the board is filled
 */
int board_is_filled(struct cell (*b)[9][9])
{
	int x = 0;
	int y = 0;

	for (x = 0; x < 9; x++) {
		for (y = 0; y < 9; y++) {
			if ((*b)[x][y].val == 0) {
				return -1;
			}
		}
	}
	return 0;
}

/*
 * Check if all of the rows on are correctly solved on a board
 * Returns 0 for all rows correctly solved
 */
int board_rows_are_solved(struct cell (*b)[9][9])
{
	int row_has[9] = {0};
	int val = 0;
	int x = 0;
	int y = 0;

	for (y = 0; y < 9; y++) {
		memset(row_has, 0, sizeof(row_has));
		for (x = 0; x < 9; x++) {
			val = (*b)[x][y].val;
			if (val == 0) {
				return -1;
			}
			if (row_has[val - 1]) {
				DEBUG_LOG("Invalid board: Row %d duplicate %d\n", y, val);
				return -1;
			}
			row_has[val - 1] = 1;
		}
	}

	return 0;
}

/*
 * Check if all of the columns on are correctly solved on a board
 * Returns 0 for all columns correctly solved
 */
int board_cols_are_solved(struct cell (*b)[9][9])
{
	int col_has[9] = {0};
	int val = 0;
	int x = 0;
	int y = 0;

	for (x = 0; x < 9; x++) {
		memset(col_has, 0, sizeof(col_has));
		for (y = 0; y < 9; y++) {
			val = (*b)[x][y].val;
			if (val == 0) {
				return -1;
			}
			if (col_has[val - 1]) {
				DEBUG_LOG("Invalid board: Column %d duplicate %d\n", x, val);
				return -1;
			}
			col_has[val - 1] = 1;
		}
	}

	return 0;
}

/*
 * Check if one of the nine 3x3 boxes is correctly solved on a board
 * Returns 0 for a correctly solved 3x3
 */
int board_box_is_solved(struct cell (*b)[9][9], int bx, int by)
{
	int col_has[9] = {0};
	int val = 0;
	int x = 0;
	int y = 0;

	bx *= 3;
	by *= 3;

	for (x = bx; x < bx + 3; x++) {
		for (y = by; y < by + 3; y++) {
			val = (*b)[x][y].val;
			if (val == 0) {
				return -1;
			}
			if (col_has[val - 1]) {
				DEBUG_LOG("Invalid board: box %d,%d duplicate %d\n", bx/3, by/3 val);
				return -1;
			}
			col_has[val - 1] = 1;
		}
	}

	return 0;
}

/*
 * Check if all of the nine 3x3 boxes are correctly solved on a board
 * Returns 0 for correctly solved boxes
 */
int board_boxes_are_solved(struct cell (*b)[9][9])
{
	int ret = 0;
	int x = 0;
	int y = 0;
	for (x = 0; x < 3; x++) {
		for (y = 0; y < 3; y++) {
			ret = board_box_is_solved(b, x, y);
			if (ret)
				return ret;
		}
	}
	return ret;
}

/*
 * Check if a board is solved.
 * Returns 0 if the board is solved correctly
 */
int board_is_solved(struct cell (*b)[9][9])
{
	int ret = 0;
	ret = board_is_filled(b);
	if (ret)
		return ret;

	ret = board_rows_are_solved(b);
	if (ret)
		return ret;

	ret = board_cols_are_solved(b);
	if (ret)
		return ret;

	ret = board_boxes_are_solved(b);

	return ret;
}