In order to make a sudoku, you need to insult the following steps one by one:
1 Create a grid and partially fill it according to an algorithm
2 Print the grid to the user
3 Ask the user for input
4 repeat step 2 and 3 until the sudoku is completed
5 check solutions
The algorithm you need is below:
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//This program solves the sudoku puzzle.
#include <iostream>
#include <cmath>
using namespace std;
void loadinput();
void printgrid();
bool checkrow(int row, int column);
bool checkcolumn(int row, int column);
bool checksquare(int row, int column);
bool solve(int row, int column);
int inputgrid[9][9];
struct Playinggrid {
int number;
bool fixed;
}
grid[9][9];
void loadinput(){
for (int i = 0; i < 9; i++){
for (int j = 0; j < 9; j++){
if (inputgrid[i][j] == 0){
grid[i][j].fixed = false;
grid[i][j].number = 0;
}
else{
grid[i][j].fixed = true;
grid[i][j].number = inputgrid[i][j];
}
}
}
}
void printgrid() {
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
cout << grid[i][j].number << " ";
}
cout << endl;
}
}
bool checkrow(int row, int column){
for (int i = 0; i < 9; i++){
if (i != column){
if (grid[row][i].number == grid[row][column].number ){
return false;
}
}
}
return true;
}
bool checkcolumn(int row, int column){
for (int i = 0; i < 9; i++){
if (i != row){
if (grid[i][column].number == grid[row][column].number ){
return false;
}
}
}
return true;
}
bool checksquare(int row, int column){
int vsquare = row/3;
int hsquare = column/3;
for (int i = vsquare * 3; i < (vsquare*3 + 3); i++){
for (int j = hsquare * 3; j < (hsquare*3 + 3); j++){
if (!(i == row && j == column)){
if (grid[ row ][ column ].number == grid[i][j].number){
return false;
}
}
}
}
return true;
}
bool solve(int row, int column){
while (grid[row][column].fixed == true)
{
column++;
if(column > 8){
column = 0;
row++;
}
if (row > 8){
return true;
}
}
for (int n = 1; n < 10; n++){
int nextrow, nextcolumn;
grid[row][column].number = n;
if ( checkcolumn(row, column)
&& checkrow(row, column)
&& checksquare(row, column)){
nextrow = row;
nextcolumn = column;
nextcolumn++;
if(nextcolumn > 8){
nextcolumn = 0;
nextrow++;
}
if (nextcolumn == 0 && nextrow == 9){
return true;
}
if(solve(nextrow, nextcolumn)){
return true;
}
}
}
grid[row][column].number = 0;
return false;
}
int main(){
solve(0, 0);
printgrid();
return 0;
}
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The algorithm was taken from http://www.cplusplus.com
Good luck!
