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sudokulib.c
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sudokulib.c
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#include "sudokulib.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ERROR_FS_WRITE 101
#define DIR_SUDOKU_INPUT "./../data/"
#define DIR_SUDOKU_OUTPUT "./../solutions/"
sudokuArray readSudoku(char *sudokuFile) {
char filename[128];
sprintf(filename, "%s%s", DIR_SUDOKU_INPUT, sudokuFile);
FILE *filePointer = fopen(filename, "r");
if (!filePointer) {
perror("Failed to open file");
printf("Unable to open file %s\n", filename);
}
int c, value, col, row, i = 0;
sudokuArray sudoku;
sudoku = (struct Field *) malloc(sizeof(struct Field *) * 9);
for (int j = 0; j < 9; j++) {
sudoku[j] = (struct Field *) malloc(sizeof(struct Field) * 9);
}
while ((c = getc(filePointer)) != EOF) {
if (c == 32) {
continue;
} else if (c >= 48 && c <= 57) {
value = c - 48;
row = i / 9;
col = i % 9;
sudoku[row][col].value = value;
if (value > 0) {
sudoku[row][col].valid = 1;
} else {
sudoku[row][col].valid = 0;
}
i++;
} else {
perror("Invalid input data structure (digits should be separated with space)");
}
}
if (i != 81) {
perror("Invalid input data length (file should has 81 space separated digits)");
}
fclose(filePointer);
return sudoku;
}
void writeSudoku(sudokuArray sudoku, char *sudokuFile) {
char filename[128];
sprintf(filename, "%s%s", DIR_SUDOKU_OUTPUT, sudokuFile);
FILE *filePointer = fopen(filename, "w+");
if (!filePointer) {
perror("Failed to open file");
printf("Unable to open file %s\n", filename);
exit(ERROR_FS_WRITE);
}
char chunk[3];
char output[256];
memset(output, 0, sizeof(output));
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
sprintf(chunk, "%d ", sudoku[row][col].value);
strcat(output, chunk);
}
}
output[strlen(output) - 1] = NULL;
fputs(output, filePointer);
fclose(filePointer);
}
void printSudoku(sudokuArray sudoku) {
for (int row = 0; row < 9; row++) {
if (row == 0) {
printf("\n_____________________________________\n");
}
for (int col = 0; col < 9; col++) {
if (col == 0) {
printf("|");
}
if (sudoku[row][col].value == 0) {
printf(" _ |");
} else {
printf(" %d |", sudoku[row][col].value);
}
}
if (row == 8) {
printf("\n-------------------------------------\n");
} else {
printf("\n|---|---|---|---|---|---|---|---|---|\n");
}
}
}
int checkSudokuConflicts(sudokuArray sudoku) {
int conflictsCount = 0;
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
int currentValue = sudoku[row][col].value;
int result = 0;
if (currentValue == 0) {
continue;
}
int i = 9;
while (i--) {
// Horizontal check
if (col != i) {
if (currentValue == sudoku[row][i].value) {
result++;
}
}
// Vertical check
if (row != i) {
if (currentValue == sudoku[i][col].value) {
result++;
}
}
// Local check
int rowOffset = (row / 3) * 3;
int colOffset = (col / 3) * 3;
int localRow = rowOffset + (i / 3);
int localCol = colOffset + (i % 3);
if (row == localRow && col == localCol) {
continue;
}
if (currentValue == sudoku[localRow][localCol].value) {
result++;
}
}
conflictsCount += result;
}
}
return conflictsCount > 1;
}
int isSudokuSolvable(sudokuArray S) {
generatePossibilites(S);
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
int possibilities = 0;
if (S[row][col].value > 0) {
continue;
}
for (int p = 1; p < 10; p++) {
if (S[row][col].possibility[p] == 1) {
possibilities++;
}
}
if (possibilities == 0) {
return 0;
}
}
}
return 1;
}
void generatePossibilites(sudokuArray S) {
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
if (S[row][col].value > 0) {
continue;
}
int currentValue = S[row][col].value;
int i = 9;
int j = 10;
while (j--) S[row][col].possibility[j] = 1;
while (i--) {
// Horizontal check
if (S[row][i].value > 0) {
S[row][col].possibility[S[row][i].value] = 0;
}
// Vertical check
if (S[i][col].value) {
S[row][col].possibility[S[i][col].value] = 0;
}
// Local check
int rowOffset = (row / 3) * 3;
int colOffset = (col / 3) * 3;
int localRow = rowOffset + (i / 3);
int localCol = colOffset + (i % 3);
if (S[localRow][localCol].value) {
S[row][col].possibility[S[localRow][localCol].value] = 0;
}
}
}
}
}
void printPossibilities(int possibility[10]) {
for (int i = 1; i < 10; i++) {
if (possibility[i] == 0) {
continue;
} else {
printf("%d ", i);
}
}
}
int countPossibilities(int possibility[10]) {
int count = 0;
for (int i = 1; i < 10; i++) {
if (possibility[i] == 0) {
continue;
} else {
count++;
}
}
return count;
}
int getBestPossibility(sudokuArray S, int R, int C) {
int counts[10];
int k = 10;
while (k--) { counts[k] = 0; }
for (int col = 0; col < 9; col++) {
for (int i = 1; i < 10; i++) {
if (S[R][col].possibility[i] == 1) {
counts[i]++;
}
}
}
int minCount = 9;
int selectedValue = 0;
for (int i = 1; i < 10; i++) {
if (S[R][C].possibility[i] == 0) {
continue;
} else {
if (counts[i] < minCount) {
minCount = counts[i];
selectedValue = i;
}
}
}
return selectedValue;
}
void resolveSudoku(sudokuArray S) {
generatePossibilites(S);
for (int p = 1; p < 9; p++) {
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
if (S[row][col].value > 0) {
continue;
}
if (countPossibilities(S[row][col].possibility) <= p) {
int value = getBestPossibility(S, row, col);
S[row][col].value = value;
generatePossibilites(S);
}
}
}
}
}