#include<stdio.h>
#include<string.h> 
struct Checkout{
	int flag;
	char type[20];
	int num;
	int place;
};

void printmat(volatile int board[9][9])
{
	int i,j;
	for (i=0;i<9;i++)
	{
		if(i%3==0) printf("|-----------------------|\n");
		for(j=0;j<9;j++)
		{
			if(j%3==0) printf(j==0?"|":" |");
			printf(" %d",board[i][j]);
		}
		printf(" |\n");
	}
	printf("|-----------------------|\n");
	return;
}

struct Checkout check(volatile int board[9][9])
{
	int checkmat[9][2][2]={{{0,0},{3,3}},
					{{0,3},{3,6}},
					{{0,6},{3,9}},
					{{3,0},{6,3}},
					{{3,3},{6,6}},
					{{3,6},{6,9}},
					{{6,0},{9,3}},
					{{6,3},{9,6}},
					{{6,6},{9,9}}};
	int i,j,k;
	struct Checkout out;
	
	for (i=0;i<9;i++)
	{
		int flag[9] = {0,0,0,0,0,0,0,0,0};
		for (j=0;j<9;j++)
		{
			if (board[i][j]!=0 )
			{
				if (flag[board[i][j]-1]==1)
				{
					//printf("False:Invalid initial Sudoku matrix\n");
					//printf("      The number %d in the row %d has been used!\n",board[i][j],i+1);
					out.flag=0;
					strcpy(out.type,"row");
					out.num=board[i][j];
					out.place=i+1;
					return out;
				}
				else flag[board[i][j]-1]=1;
			}
		}
	}
	
	for (i=0;i<9;i++)
	{
		int flag[9] = {0,0,0,0,0,0,0,0,0};
		for (j=0;j<9;j++)
		{
			if (board[j][i]!=0 )
			{
				if (flag[board[j][i]-1]==1)
				{
					//printf("False:Invalid initial Sudoku matrix\n");
					//printf("      The number %d in the col %d has been used!\n",board[j][i],i+1);
					out.flag=0;
					strcpy(out.type,"col");
					out.num=board[j][i];
					out.place=i+1;
					return out;
				}
				else flag[board[j][i]-1]=1;
			}
		}
	}
	
	for (k=0;k<9;k++)
	{
		int flag[9] = {0,0,0,0,0,0,0,0,0};
		for (i=checkmat[k][0][0];i<checkmat[k][1][0];i++)
		{
			for (j=checkmat[k][0][1];j<checkmat[k][1][1];j++)
			{
				if (board[i][j]!=0 )
				{
					if (flag[board[i][j]-1]==1)
					{
						//printf("False:Invalid initial Sudoku matrix\n");
						//printf("      The number %d in the block %d has been used!\n",board[i][j],k+1);
						out.flag=0;
						strcpy(out.type,"block");
						out.num=board[i][j];
						out.place=k+1;
						return out;
					}
					else flag[board[i][j]-1]=1;
				}
			}
		}
	}
	//printf("True:Valid initial Sudoku matrix!\n");
	out.flag=1;
	return out;
}

int sv=0;

int solve(volatile int board[9][9],int cnt)
{	
	if (cnt==0)
	{
		if(!sv) printf("The solution of Sudoku martix:\n");
		printmat(board);
		sv=1;
		return 1;
	}
	else
	{
		//printf("check %d\n",cnt);
		int i,j,num;
		for(i=0;i<9;i++)
		{
			for(j=0;j<9;j++)
			{
				if(board[i][j]==0)
				{
					for(num=1;num<10;num++)
					{
						board[i][j]=num;
						//printf("%d %d %d\n",i,j,num);
						if(check(board).flag)
						{
							if(solve(board,cnt-1)) return 1;
						}
					}
					board[i][j]=0;
					return 0;
				}
			}
		}
	}
	
}

int main()
{
	volatile int board[9][9]={{5, 3, 0, 0, 7, 0, 0, 0, 0},
					{6, 0, 0, 1, 9, 5, 0, 0, 0},
					{0, 9, 8, 0, 0, 0, 0, 6, 0},
					{8, 0, 0, 0, 6, 0, 0, 0, 3},
					{4, 0, 0, 8, 0, 3, 0, 0, 1},
					{7, 0, 0, 0, 2, 0, 0, 0, 6},
					{0, 6, 0, 0, 0, 0, 2, 8, 0},
					{0, 0, 0, 4, 1, 9, 0, 0, 5},
					{0, 0, 0, 0, 8, 0, 0, 7, 9}};
	int i,j,k,cnt=0;
	printf("The original Sudoku matrix\n");
	printmat(board);
	struct Checkout out=check(board);
	if (!out.flag)
	{
		printf("False:Invalid initial Sudoku matrix\n");
		printf("      The number %d in the %s %d has been used!\n",out.num,out.type,out.place);
		printf("No solusion!");
		return 0;
	}
	printf("True:Valid initial Sudoku matrix!\n");
	for (i=0;i<9;i++) for(j=0;j<9;j++) if(board[i][j]==0) cnt++;
	solve(board,cnt);
	if (!sv) printf("No solusion!");
	return 0;
}