knight's tour problem

knight.c

#include<stdio.h>
#define true 1
#define false 0
#define size 8
//function declarations 

void printsolution(int sol[][size]);
int solvetour(int x,int y, int nextmove, int sol[][size],int a[],int b[]);
int issafe(int x, int y, int sol[][size]);

//main starts

int main()
{
	int i,j;
	
	int sol[size][size];
	
	int a[8] = {2,-1, -2,  1, -1, -2, 1, 2};
	int b[8] = {1, 2, -1, -2, -2,  1, 2,-1};
	// possible 8 movement of the  knight
	
	for(i=0;i<size;i++)           //initializing the solution array
		for(j=0;j<size;j++)
			sol[i][j]=0;
			
	if(solvetour(0,0,1,sol,a,b)==false)
	{
		printf("no tour exists");
		return false;
	}
	else
	{
		printsolution(sol);
	}
	return 0;
}

int solvetour(int x,int y, int nextmove, int sol[][size],int a[],int b[])
{
	int i,xnew,ynew;
	if(nextmove == size*size)return true;   // base condition
	else
	{
		// work starts here, 
		for(i=0;i<size;i++)
		{
			xnew = x+a[i];      //select next move
			ynew = y+b[i];   
			
			if(issafe(xnew,ynew,sol))
			{
				sol[xnew][ynew] = nextmove;
				if(solvetour(xnew,ynew,nextmove+1,sol,a,b))
				return true;
				else
				sol[xnew][ynew] = 0;   // backtrack
			}
		}
	}
	return false;
}

int issafe(int x, int y, int sol[][size])
{
	if((x>=0)&&(x<size)&&(y>=0)&&(y<size)&&sol[x][y]==0)
	return true;
	return false;
}
	
void printsolution(int sol[][size])
{
	int i,j;
	for(i=0;i<size;i++)
	{
		for(j=0;j<size;j++)
		{
			printf("%2d ",sol[i][j]);
		}
		printf("\n");
	}
}