/****************************************************************************
* apps/system/sudoku/sudoku.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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 OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "system/readline.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NHISTORY 16
/****************************************************************************
* Private Types
****************************************************************************/
struct sudoku_s
{
uint16_t canbe;
uint16_t is;
};
typedef struct sudoku_s sudoku_t[81];
/****************************************************************************
* Private Data
****************************************************************************/
static sudoku_t history[NHISTORY];
static sudoku_t working;
static int first;
static int last;
static int current;
static const char *r1[8] =
{" ", "1 ", " 2 ", "12 ", " 3", "1 3", " 23", "123" };
static const char *r2[8] =
{" ", "4 ", " 5 ", "45 ", " 6", "4 6", " 56", "456" };
static const char *r3[8] =
{" ", "7 ", " 8 ", "78 ", " 9", "7 9", " 89", "789" };
static char line[256];
static int nis = 0;
/****************************************************************************
* Private Functions
****************************************************************************/
static inline void init_array(void)
{
int i;
first = 0;
last = 0;
current = 0;
for (i = 0; i < 81; i++)
{
working[i].canbe = 0x1ff;
working[i].is = 0x000;
}
}
static inline void push(void)
{
int next = current + 1;
if (next >= NHISTORY) next = 0;
if (current == last)
{
last = next;
}
if (first == next)
{
if (++first >= NHISTORY) first = 0;
}
memcpy (history[current], working, sizeof(sudoku_t));
current = next;
}
static inline void undo(void)
{
if (current == first)
{
printf("Cannot undo\n");
}
else
{
if (--current < 0) current = NHISTORY-1;
memcpy (working, history[current], sizeof(sudoku_t));
}
}
static inline void redo(void)
{
if (current == last)
{
printf("Cannot redo\n");
}
else
{
if (++current >= NHISTORY) current = 0;
memcpy(working, history[current], sizeof(sudoku_t));
}
}
static inline void show_row(int row)
{
printf(" |%3s|%3s|%3s| |%3s|%3s|%3s| |%3s|%3s|%3s|\n",
r1[working[9*row + 0].canbe & 0x007],
r1[working[9*row + 1].canbe & 0x007],
r1[working[9*row + 2].canbe & 0x007],
r1[working[9*row + 3].canbe & 0x007],
r1[working[9*row + 4].canbe & 0x007],
r1[working[9*row + 5].canbe & 0x007],
r1[working[9*row + 6].canbe & 0x007],
r1[working[9*row + 7].canbe & 0x007],
r1[working[9*row + 8].canbe & 0x007]);
printf(" %2d |%3s|%3s|%3s| |%3s|%3s|%3s| |%3s|%3s|%3s|\n", row + 1,
r2[(working[9*row + 0].canbe >> 3) & 0x007],
r2[(working[9*row + 1].canbe >> 3) & 0x007],
r2[(working[9*row + 2].canbe >> 3) & 0x007],
r2[(working[9*row + 3].canbe >> 3) & 0x007],
r2[(working[9*row + 4].canbe >> 3) & 0x007],
r2[(working[9*row + 5].canbe >> 3) & 0x007],
r2[(working[9*row + 6].canbe >> 3) & 0x007],
r2[(working[9*row + 7].canbe >> 3) & 0x007],
r2[(working[9*row + 8].canbe >> 3) & 0x007]);
printf(" |%3s|%3s|%3s| |%3s|%3s|%3s| |%3s|%3s|%3s|\n",
r3[(working[9*row + 0].canbe >> 6) & 0x007],
r3[(working[9*row + 1].canbe >> 6) & 0x007],
r3[(working[9*row + 2].canbe >> 6) & 0x007],
r3[(working[9*row + 3].canbe >> 6) & 0x007],
r3[(working[9*row + 4].canbe >> 6) & 0x007],
r3[(working[9*row + 5].canbe >> 6) & 0x007],
r3[(working[9*row + 6].canbe >> 6) & 0x007],
r3[(working[9*row + 7].canbe >> 6) & 0x007],
r3[(working[9*row + 8].canbe >> 6) & 0x007]);
}
static inline void show_array(void)
{
int row;
int i;
printf(" +===+===+===+ +===+===+===+ +===+===+===+\n");
printf(" | 1 | 2 | 3 | | 4 | 5 | 6 | | 7 | 8 | 9 |\n");
printf(" +===+===+===+ +===+===+===+ +===+===+===+\n");
row = 0;
for (i = 0; i < 3; i++)
{
show_row(row++);
printf(" +---+---+---+ +---+---+---+ +---+---+---+\n");
show_row(row++);
printf(" +---+---+---+ +---+---+---+ +---+---+---+\n");
show_row(row++);
printf(" +===+===+===+ +===+===+===+ +===+===+===+\n");
}
}
static inline int is_unique(unsigned int val)
{
switch (val)
{
case 0x001:
case 0x002:
case 0x004:
case 0x008:
case 0x010:
case 0x020:
case 0x040:
case 0x080:
case 0x100:
return 1;
default:
return 0;
}
}
static inline int impossible(void)
{
int nchanges = 0;
unsigned int val;
int row1, col1;
int row2, col2;
int i, j;
int ndx1, ndx2;
for (row1 = 0; row1 < 9; row1++)
{
row2 = row1 / 3;
for (col1 = 0; col1 < 9; col1++)
{
col2 = col1 / 3;
ndx1 = row1*9 + col1;
val = working[ndx1].canbe;
for (i = 0; i < 9; i++)
{
ndx2 = i*9 + col1;
if (ndx1 != ndx2)
{
val &= ~working[ndx2].is;
}
}
for (j = 0; j < 9; j++)
{
ndx2 = row1*9 + j;
if (ndx1 != ndx2)
{
val &= ~working[ndx2].is;
}
}
for (i = 0; i < 3; i++)
{
for (j = 0; j < 3; j++)
{
ndx2 = (row2*3 + i)*9 + (col2*3 + j);
if (ndx1 != ndx2)
{
val &= ~working[ndx2].is;
}
}
}
if (val == 0)
{
return -1;
}
if (val != working[ndx1].canbe)
{
nchanges++;
working[ndx1].canbe = val;
if (is_unique(val))
{
working[ndx1].is = val;
}
}
}
}
return nchanges;
}
static inline int unique(void)
{
int noccurences[9];
int lastndx[9];
int nchanges = 0;
unsigned int mask;
unsigned int val;
int row1, col1;
int row2, col2;
int ndx;
int i;
for (row1 = 0; row1 < 9; row1++)
{
for (i = 0; i < 9; i++)
{
noccurences[i] = 0;
lastndx[i] = -1;
}
for (i = 0; i < 9; i++)
{
mask = 1 << i;
for (col1 = 0; col1 < 9; col1++)
{
ndx = row1 * 9 + col1;
if (working[ndx].canbe & mask)
{
noccurences[i]++;
lastndx[i] = ndx;
}
}
for (i = 0; i < 9; i++)
{
if (noccurences[i] == 1)
{
val = 1 << i;
ndx = lastndx[i];
if (working[ndx].is != val)
{
working[ndx].is = val;
working[ndx].canbe = val;
nchanges++;
}
}
}
}
}
for (col1 = 0; col1 < 9; col1++)
{
for (i = 0; i < 9; i++)
{
noccurences[i] = 0;
lastndx[i] = -1;
}
for (i = 0; i < 9; i++)
{
mask = 1 << i;
for (row1 = 0; row1 < 9; row1++)
{
ndx = row1 * 9 + col1;
if (working[ndx].canbe & mask)
{
noccurences[i]++;
lastndx[i] = ndx;
}
}
for (i = 0; i < 9; i++)
{
if (noccurences[i] == 1)
{
val = 1 << i;
ndx = lastndx[i];
if (working[ndx].is != val)
{
working[ndx].is = val;
working[ndx].canbe = val;
nchanges++;
}
}
}
}
}
for (row2 = 0; row2 < 3; row2++)
{
for (col2 = 0; col2 < 3; col2++)
{
for (i = 0; i < 9; i++)
{
noccurences[i] = 0;
lastndx[i] = -1;
}
for (i = 0; i < 9; i++)
{
mask = 1 << i;
for ( row1 = 0; row1 < 3; row1++)
{
for ( col1 = 0; col1 < 3; col1++)
{
ndx = (row2*3 + row1)*9 + (col2*3 + col1);
if (working[ndx].canbe & mask)
{
noccurences[i]++;
lastndx[i] = ndx;
}
}
}
}
for (i = 0; i < 9; i++)
{
if (noccurences[i] == 1)
{
val = 1 << i;
ndx = lastndx[i];
if (working[ndx].is != val)
{
working[ndx].is = val;
working[ndx].canbe = val;
nchanges++;
}
}
}
}
}
return nchanges;
}
static inline int getcell(int *pndx, int *pval)
{
int row, col, ndx;
unsigned int val;
int i = 0;
while ((line[i] == ' ' || line[i] == '\t') && (line[i] != '\0') && (line[i] != '\n')) i++;
if (line[i] < '1' || line[i] > '9')
{
printf("Bad row: %c\n", line[i]);
return -1;
}
row = line[i++] -'0' - 1;
while ((line[i] == ' ' || line[i] == '\t') && (line[i] != '\0') && (line[i] != '\n')) i++;
if (line[i] < '1' || line[i] > '9')
{
printf("Bad col: %c\n", line[i]);
return -1;
}
col = line[i++] -'0' - 1;
ndx = row*9 + col;
while ((line[i] == ' ' || line[i] == '\t') && (line[i] != '\0') && (line[i] != '\n')) i++;
if (line[i] < '1' || line[i] > '9')
{
printf("Bad value: %c\n", line[i]);
return -1;
}
val = 1 << ((line[i] - '0') - 1);
if (( val & working[ndx].canbe) == 0)
{
printf("Impossible value: %c\n", line[i]);
return -1;
}
*pndx = ndx;
*pval = val;
return 0;
}
static inline int get_command(void)
{
printf("%d of 81> ", nis);
fflush(stdout);
(void)readline(line, 256, stdin, stdout);
int i = 0;
while ((line[i] == ' ' || line[i] == '\t') && (line[i] != '\0') && (line[i] != '\n')) i++;
return line[i];
}
static inline void show_usage(void)
{
printf("ABC - Set cell[A,B] to C where A,B, and C are in {1..9}\n");
printf("U - Undo last cell assignment\n");
printf("R - Redo last cell assignment\n");
printf("H|? - Show this message\n");
printf("Q - Quit\n");
}
static inline void count_cells(void)
{
int i;
nis = 0;
for (i = 0; i < 81; i++) if (working[i].is > 0) nis++;
}
/****************************************************************************
* Private Functions
****************************************************************************/
#ifdef BUILD_MODULE
int main(int argc, FAR char *argv[])
#else
int sudoku_main(int argc, char **argv, char **envp)
#endif
{
int cmd;
int nchanged;
int val;
int ndx;
init_array();
for (;;)
{
count_cells();
show_array();
if (nis == 81)
{
printf("GAME OVER: 81 of 81 assigned\n");
return 0;
}
else
{
cmd = get_command();
switch (cmd)
{
case 'U':
case 'u':
undo();
break;
case 'R':
case 'r':
redo();
break;
case 'H':
case 'h':
case '?':
show_usage();
break;
case 'Q':
case 'q':
return 0;
default:
if (getcell(&ndx, &val) == 0)
{
push();
working[ndx].is = val;
working[ndx].canbe = val;
for (;;)
{
nchanged = impossible();
if (nchanged < 0)
{
printf("This move is not possible\n");
undo();
break;
}
else if (nchanged == 0)
{
nchanged = unique();
if (nchanged == 0)
{
break;
}
}
}
}
}
}
}
}