Sudoku.c

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<pthread.h>
#define N 27

int valid[N] = {0};

typedef struct
{
	int row;
	int column;		
} pos;

int sudoku[9][9];

sudoku[9][9] = {
	{6, 2, 4, 5, 3, 9, 1, 8, 7},
	{5, 1, 9, 7, 2, 8, 6, 3, 4},
	{8, 3, 7, 6, 1, 4, 2, 9, 5},
	{1, 4, 3, 8, 6, 5, 7, 2, 9},
	{9, 5, 8, 2, 4, 7, 3, 6, 1},
	{7, 6, 2, 3, 9, 1, 4, 5, 8},
	{3, 7, 1, 9, 5, 6, 8, 4, 2},
	{4, 9, 6, 1, 8, 2, 5, 7, 3},
	{2, 8, 5, 4, 7, 3, 9, 1, 6}
};


void *isColumnValid(void* param) 
{
	pos *p = (pos*) param;
	int row = p->row;
	int col = p->column;		
	if (row != 0 || col > 8) 
	{
		printf("Invalid row or column for col subsection! row=%d, col=%d\n", row, col);
		pthread_exit(NULL);
	}

	
	int validityArray[9] = {0};
	int i;	
	for (i = 0; i < 9; i++) 
	{
		int num = sudoku[i][col];
		if (num < 1 || num > 9 || validityArray[num - 1] == 1){
			pthread_exit(NULL);
		}else{
			validityArray[num - 1] = 1;		
		}
	}
	
	valid[18 + col] = 1;
	pthread_exit(NULL);
}


void *isRowValid(void* param) 
{
	
	pos *p = (pos*) param;
	int row = p->row;
	int col = p->column;		
	if (col != 0 || row > 8) {
		printf("Invalid row or column for row subsection! row=%d, col=%d\n", row, col);
		pthread_exit(NULL);
	}

	int validityArray[9] = {0};
	int i;
	for (i = 0; i < 9; i++){
		
		int num = sudoku[row][i];
		if (num < 1 || num > 9 || validityArray[num - 1] == 1){
			pthread_exit(NULL);
		}else{
			validityArray[num - 1] = 1;		
		}
	}
	
	valid[9 + row] = 1;
	pthread_exit(NULL);
}


void *is3x3Valid(void* param) 
{
	
	pos *p = (pos*) param;
	int row = p->row;
	int col = p->column;		
	if (row > 6 || row % 3 != 0 || col > 6 || col % 3 != 0) 
	{
		printf("Invalid row or column for subsection! row=%d, col=%d\n", row, col);
		pthread_exit(NULL);
	}
	int validityArray[9] = {0};
	int i, j;
	for (i = row; i < row + 3; i++) 
	{
		for (j = col; j < col + 3; j++) 
		{
			int num = sudoku[i][j];
			if (num < 1 || num > 9 || validityArray[num - 1] == 1){
				pthread_exit(NULL);
			}else{
				validityArray[num - 1] = 1;		
			}
		}
	}
	
	valid[row + col/3] = 1; 
	pthread_exit(NULL);
}

int main() 
{	
	pthread_t threads[N];
	int threadIndex = 0;	
	int i,j;
	//int sudoku[9][9];
	printf("enter sudoku matrix\n");
	for(i=0;i<9;i++)
	{
		for(j=0;j<9;j++)
		{
			scanf("%d",&sudoku[i][j]);
		}
		printf("\n");
	}
	
	for (i = 0; i < 9; i++) 
	{
		for (j = 0; j < 9; j++) 
		{						
			if (i%3 == 0 && j%3 == 0){
				pos *data = (pos *) malloc(sizeof(pos));	
				data->row = i;		
				data->column = j;
				pthread_create(&threads[threadIndex++], NULL, is3x3Valid, data); 
			}
			if (i == 0){
				pos *columnData = (pos *) malloc(sizeof(pos));	
				columnData->row = i;		
				columnData->column = j;
				pthread_create(&threads[threadIndex++], NULL, isColumnValid, columnData);	
			}
			if (j == 0){
				pos *rowData = (pos *) malloc(sizeof(pos));	
				rowData->row = i;		
				rowData->column = j;
				pthread_create(&threads[threadIndex++], NULL, isRowValid, rowData); 
			}
		}
	}

	for (i = 0; i < N; i++){
		pthread_join(threads[i], NULL);			
	}

	for (i = 0; i < N; i++){
		if (valid[i] == 0){
			printf("Sudoku solution is invalid!\n");
			return EXIT_SUCCESS;
		}
	}
	printf("Sudoku solution is valid!\n");
	return EXIT_SUCCESS;
}