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| // sudoku_solver.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
typedef struct cell {
int val;
int init;
} cell;
typedef struct sudoku_stats {
unsigned int row[9];
unsigned int col[9];
unsigned int box[9];
} sudoku_stats;
#define ANSI_COLOR_RED "\x1b[31m"
#define ANSI_COLOR_GREEN "\x1b[32m"
#define ANSI_COLOR_YELLOW "\x1b[33m"
#define ANSI_COLOR_BLUE "\x1b[34m"
#define ANSI_COLOR_MAGENTA "\x1b[35m"
#define ANSI_COLOR_CYAN "\x1b[36m"
#define ANSI_COLOR_RESET "\x1b[0m"
static int num_solved;
int sudoku_parser(cell **grid, FILE *f);
int sudoku_preprocessor(cell **grid, sudoku_stats *st);
void sudoku_printer(cell **grid);
void sudoku_solver_row(cell **grid, sudoku_stats *st);
void sudoku_solver_box(cell **grid, sudoku_stats *st);
void sudoku_solver_cell(cell **grid, sudoku_stats *st);
void sudoku_solver_column(cell **grid, sudoku_stats *st);
static void sudoku_printStats(sudoku_stats *st);
static inline int count_ones(int a)
{
int c = 0;
while (a) {
c++;
a = a & (a-1);
}
return c;
}
int sudoku_parser(cell **grid, FILE *f)
{
char buf[64];
int nums[9];
for (int row = 0; row < 9; row++) {
fgets(buf, 20, f);
sscanf(buf, "%d,%d,%d,%d,%d,%d,%d,%d,%d",
&grid[row][0].val,
&grid[row][1].val,
&grid[row][2].val,
&grid[row][3].val,
&grid[row][4].val,
&grid[row][5].val,
&grid[row][6].val,
&grid[row][7].val,
&grid[row][8].val);
}
return 0;
}
int sudoku_preprocessor(cell **grid, sudoku_stats *st)
{
for (int k = 0; k < 9; k++) {
st->row[k] = 0x1FF;
st->col[k] = 0x1FF;
st->box[k] = 0x1FF;
}
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
if (grid[i][j].val != 0) {
grid[i][j].init = 1;
num_solved++;
}
st->row[i] &= ~(1 << (grid[i][j].val - 1));
st->col[j] &= ~(1 << (grid[i][j].val - 1));
st->box[3*(i/3) + (j/3)] &= ~(1 << (grid[i][j].val - 1));
}
}
//sudoku_printStats(st);
}
static void sudoku_printStats(sudoku_stats *st)
{
// For debugging purposes
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
printf("%2c", ((1 << j) & st->row[i]) ? '1' : '0');
}
printf("\t");
for (int j = 0; j < 9; j++) {
printf("%2c", ((1 << j) & st->col[i]) ? '1' : '0');
}
printf("\t");
for (int j = 0; j < 9; j++) {
printf("%2c", ((1 << j) & st->box[i]) ? '1' : '0');
}
printf("\n");
}
}
static char ans;
int main(int argc, char *argv[])
{
int m_siz = 9;
cell **grid = (cell**)malloc(m_siz*sizeof(cell*));
for (int i = 0; i < m_siz; i++) {
grid[i] = (cell*) malloc(m_siz * sizeof(cell));
memset(grid[i], 0, 9*sizeof(**grid));
}
FILE *test_file;
if (argc > 1) {
test_file = fopen(argv[1], "r");
} else {
test_file = fopen("test/puzzle.txt", "r");
}
int num_solved_prev = 0;
sudoku_stats g_stats;
printf("Parsed puzzle res %d\n\n", sudoku_parser(grid, test_file));
sudoku_preprocessor(grid, &g_stats);
sudoku_printer(grid);
while (num_solved_prev != num_solved) {
num_solved_prev = num_solved;
sudoku_solver_row(grid, &g_stats);
sudoku_solver_cell(grid, &g_stats);
sudoku_solver_box(grid, &g_stats);
sudoku_solver_column(grid, &g_stats);
}
sudoku_printer(grid);
for (int i = 0; i < m_siz; i++)
free(grid[i]);
free(grid);
}
void sudoku_solver_box(cell **grid, sudoku_stats *st)
{
for (int b = 0; b < 9; b++) {
for (int e = 0; e < 9; e++) {
unsigned int avl = 0x01FF;
if (st->box[b] & (1 << e)) {
for (int x = 0; x < 9; x++) {
if (grid[3*(b/3) + x/3][3*(b%3) + (x%3)].val)
avl &= ~(1 << x);
}
for (int z = 0; z < 3; z++) {
if ((st->row[3*(b/3) + z] & (1 << e)) == 0) {
avl &= ~(0x00000007 << 3*z);
}
// + z][3*(b%3) + z].val || ((st->col[c] & (1 << e)) == 0))
if ((st->col[3*(b%3) + z] & (1 << e)) == 0) {
avl &= ~(0x00000049 << z);
}
}
int num;
if ((num = count_ones(avl)) == 1) {
int v = 0;
while (avl) {
avl >>= 1;
v++;
}
int x = 3*(b/3) + ((v-1)/3);
int y = 3*(b%3) + ((v-1)%3);
grid[x][y].val = e+1;
num_solved++;
st->row[3*(b/3) + ((v-1)/3)] &= ~(1<<e);
st->col[3*(b%3) + ((v-1)%3)] &= ~(1<<e);
st->box[b] &= ~(1<<e);
printf("Box solver put %d @ [%d,%d]\n", e+1, x, y);
//sudoku_printer(grid);
//sudoku_printStats(st);
//ans = (char) getchar();
} else {
//printf("gave up on %d @ box %d : p %d\n", e+1, b+1, num);
}
}
}
}
}
void sudoku_solver_row(cell **grid, sudoku_stats *st)
{
// Brute force approach:
// Iterate through each square:
for (int r = 0; r < 9; r++) {
for (int e = 0; e < 9; e++) {
unsigned int avl = 0x01FF;
if (st->row[r] & (1 << e)) {
for (int c = 0; c < 9; c++) {
if (grid[r][c].val || ((st->col[c] & (1 << e)) == 0))
avl &= ~(1 << c);
}
for (int b = 0; b < 3; b++) {
if ((st->box[3*(r/3) + b] & (1 << e)) == 0)
avl &= ~(0x00000007 << (3*b));
}
int num;
if ((num = count_ones(avl)) == 1) {
int v = 0;
while (avl) {
avl >>= 1;
v++;
}
grid[r][v-1].val = e+1;
st->row[r] &= ~(1<<e);
st->col[v-1] &= ~(1<<e);
st->box[3*(r/3) + ((v-1)/3)] &= ~(1<<e);
num_solved++;
printf("Row solver put %d @ [%d,%d]\n", e+1, r, v-1);
//sudoku_printer(grid);
//sudoku_printStats(st);
//ans = (char) getchar();
} else {
//printf("gave up on %d @ row %d : p %d\n", e+1, r+1, num);
}
}
}
}
}
void sudoku_solver_column(cell **grid, sudoku_stats *st)
{
for (int c = 0; c < 9; c++) {
for (int e = 0; e < 9; e++) {
unsigned int avl = 0x01FF;
if (st->col[c] & (1 << e)) {
for (int r = 0; r < 9; r++) {
if (grid[r][c].val || ((st->row[r] & (1 << e)) == 0)) {
avl &= ~(1 << r);
}
}
for (int b = 0; b < 3; b++) {
if ((st->box[c/3 + 3*b] & (1 << e)) == 0)
avl &= ~(0x00000007 << (3*b));
}
int num;
if ((num = count_ones(avl)) == 1) {
int v = log2(avl);
grid[v][c].val = e+1;
st->row[v] &= ~(1 << e);
st->col[c] &= ~(1 << e);
st->box[3*(v/3) + c/3] &= ~(1 << e);
num_solved++;
printf("Col solver put %d @ [%d,%d]\n", e+1, v, c);
}
}
}
}
}
void sudoku_solver_cell(cell **grid, sudoku_stats *st) {
for (int r = 0; r < 9; r++) {
for (int c = 0; c < 9; c++) {
if (grid[r][c].val != 0) {
continue;
}
int avl = 0x1FF;
avl &= st->row[r];
avl &= st->col[c];
avl &= st->box[3*(r/3) + (c/3)];
if (count_ones(avl) == 1) {
grid[r][c].val = log2(avl) + 1;
num_solved++;
st->row[r] &= ~(avl);
st->col[c] &= ~avl;
st->box[3*(r/3) + (c/3)] &= ~avl;
//sudoku_printer(grid);
printf("Cell solver put %d @ [%d,%d]\n", grid[r][c].val, r, c);
//ans = getchar();
}
}
}
}
void sudoku_printer(cell **grid)
{
printf(" +");
for (int k = 0; k < 9; k++) {
printf("%2c", '-');
if (!((k+1) % 3))
printf("%2c",'+');
}
printf("\n");
for (int i = 0; i < 9; i++) {
printf("%2c",'|');
for (int j = 0; j < 9; j++) {
if (grid[i][j].init == 1) {
printf(ANSI_COLOR_GREEN "%2d" ANSI_COLOR_RESET, grid[i][j].val);
} else {
if (grid[i][j].val != 0) {
printf(ANSI_COLOR_RED "%2d" ANSI_COLOR_RESET, grid[i][j].val);
} else {
printf("%2c", ' ');
}
}
if (!((j+1) % 3))
printf("%2c",'|');
}
printf("\n");
if (!((i+1) % 3)) {
printf("%2c", '+');
for (int k = 0; k < 9; k++) {
printf("%2c", '-');
if (!((k+1) % 3))
printf("%2c",'+');
}
printf("\n");
}
}
}
|
