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#include "sudoku.h"
Sudoku::Sudoku()
{
}
void Sudoku::set_value(int row, int column, int value)
{
sudoku_cell[row][column].set_value(value);
}
int Sudoku::solve_step(int pos_row, int pos_column)
{
// verify if the cell has already been solved
if ((value(pos_row,pos_column) > 0 ) && (value(pos_row,pos_column) <= 9)) {
return value(pos_row,pos_column);
}
bool possible_solution[9];
for (int idx = 0; idx < 9; idx++) {
possible_solution[idx] = true;
}
// eliminate row
for (int column = 0; column < 9; column++) {
if (column != pos_column) {
const int v = value(pos_row,column);
if ((v > 0) && (v <= 9)) {
possible_solution[v - 1] = false;
}
}
}
// eliminate column
for (int row = 0; row < 9; row++) {
if (row != pos_row) {
const int v = value(row,pos_column);
if ((v > 0) && (v <= 9)) {
possible_solution[v - 1] = false;
}
}
}
// eliminate subgrid
int grid_row = pos_row - (pos_row % 3);
int grid_column = pos_column - (pos_column % 3);
for (int row = grid_row; row < grid_row + 3; row++) {
for (int column = grid_column; column < grid_column + 3; column ++) {
if ((column != pos_column) && (row != pos_row)) {
const int v = value(row, column);
if ((v > 0) && (v <= 9)) {
possible_solution[v - 1] = false;
}
}
}
}
int nbeliminated = 0;
int solution = 0;
for (int idx = 0; idx < 9; idx++) {
if (!possible_solution[idx]) {
nbeliminated++;
} else {
solution = idx + 1;
}
}
if (nbeliminated == 8) {
return solution;
} else {
return 0;
}
}
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