#include <stdio.h>
#include <conio.h>
#include <windows.h>

void gotoXY(int x, int y) {
	COORD coord = { x, y };
	SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
	return;
}


void getCursorXY(int &x, int&y) {
	CONSOLE_SCREEN_BUFFER_INFO csbi;
	if (GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi)) {
		x = csbi.dwCursorPosition.X;
		y = csbi.dwCursorPosition.Y;
	}
}



int readKey()
{
	int key = 0;
	if (kbhit())
	{
		key = getch();      /* a key was pressed; read it */
		if (key == 0)       /* if zero, this is a two-char Fn key */
			key = -getch();  /* read 2nd char & return as negative */
	}                      /* to signal that this is an F-key */
	return key;
}

int isAvailable(int puzzle[][9], int row, int col, int num)
{
	int rowStart = (row / 3) * 3;
	int colStart = (col / 3) * 3;
	int i, j;

	for (i = 0; i<9; ++i)
	{
		if (puzzle[row][i] == num) return 0;
		if (puzzle[i][col] == num) return 0;
		if (puzzle[rowStart + (i % 3)][colStart + (i / 3)] == num) return 0;
	}
	return 1;
}

int fillSudoku(int puzzle[][9], int row, int col)
{
	int i;
	if (row<9 && col<9)
	{
		if (puzzle[row][col] != 0)
		{
			if ((col + 1)<9) return fillSudoku(puzzle, row, col + 1);
			else if ((row + 1)<9) return fillSudoku(puzzle, row + 1, 0);
			else return 1;
		}
		else
		{
			for (i = 0; i<9; ++i)
			{
				if (isAvailable(puzzle, row, col, i + 1))
				{
					puzzle[row][col] = i + 1;
					if ((col + 1)<9)
					{
						if (fillSudoku(puzzle, row, col + 1)) return 1;
						else puzzle[row][col] = 0;
					}
					else if ((row + 1)<9)
					{
						if (fillSudoku(puzzle, row + 1, 0)) return 1;
						else puzzle[row][col] = 0;
					}
					else return 1;
				}
			}
		}
		return 0;
	}
	else return 1;
}

void PrintSudoku(int puzzle[9][9]) {
	int j, i;

	gotoXY(0, 0);
	for (i = 0; i<9; ++i)
	{
		printf("{");
		for (j = 0; j<9; ++j) {
			printf("%1d", puzzle[i][j]);
			if (j<8) printf(",");
		}
		printf("}\n");
	}
	printf("(r)eset   (s)solve   (q)uit\n");
}

void ResetSudoku(int puzzle[9][9]) {
	int j, i;

	gotoXY(0, 0);
	for (i = 0; i<9; ++i)
	{
		printf("{");
		for (j = 0; j<9; ++j) {
			puzzle[i][j] = 0;
			printf("%1d", puzzle[i][j]);
			if (j<8) printf(",");
		}
		printf("}\n");
	}
}





int main()
{
	int i = 0, j = 0;
	int puzzle[9][9];
	/*					={{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0},
	{0, 0, 0, 0, 0, 0, 0, 0, 0}};
	*/

	char c;
	int xx;
	int yy;

	ResetSudoku(puzzle);

	system("cls");
	PrintSudoku(puzzle);

	gotoXY(1, 0);

	do {
		c = readKey();
		//		if (c!=0) printf("%d",c);

		if (c == -32) {
			c = readKey();
			//			printf(",%d",c);
			switch (c)
			{
			case 72:
				if (j>0) j--;
				break;
			case 80:
				if (j<8) j++;
				break;
			case 75:
				if (i>0) i--;
				break;
			case 77:
				if (i<8) { i++; }
				break;
			}
			xx = i * 2 + 1;
			yy = j;
			//			gotoXY(0,10);
			//			printf("   %d   ",c);

		}
		else {
			switch (c)
			{
			case 13:
				i = 0;
				if (j<8) j++;
				xx = i * 2 + 1;
				yy = j;
				break;
			case '0':
				puzzle[j][i] = c - '0';
				printf("%1d", puzzle[j][i]);
				if (i<8) {
					i++;
					xx = i * 2 + 1;
				}
				yy = j;
				gotoXY(xx, yy);
				break;

			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
				if (isAvailable(puzzle, j, i, c - '0')) {
					puzzle[j][i] = c - '0';
					printf("%1d", puzzle[j][i]);
					if (i<8) {
						i++;
						xx = i * 2 + 1;
					}
					yy = j;
					gotoXY(xx, yy);
				}
				break;
			case 'r':
				ResetSudoku(puzzle);
				break;
			case 's':
				fillSudoku(puzzle, 0, 0);
				PrintSudoku(puzzle);
				break;
			}
		}

		gotoXY(xx, yy);
		//		if (c!=0) printf("%1d",puzzle[j][i]);
	} while (c != 'q');
	gotoXY(0, 10);
	return(0);
}