/*program to check if given square is a magic square or not*/
/*A magic square is a square array of positive integers such that the sum of each row, column, and diagonal is the same constant*/
#include<stdio.h>

int ifMagicSq(int *a,int);

int main()
{
	int order=4;
	int *a;

	a=(int *)malloc(sizeof(int )*(order*order));
	
	/*enter a matrix which is a magic square - modify this to check if code works*/
	*(a+0)=16;
	*(a+1)=3;
	*(a+2)=2;
	*(a+3)=13;
	*(a+4)=5;
	*(a+5)=10;
	*(a+6)=11;
	*(a+7)=8;
	*(a+8)=9;
	*(a+9)=6;
	*(a+10)=7;
	*(a+11)=12;
	*(a+12)=4;
	*(a+13)=15;
	*(a+14)=14;
	*(a+15)=1;

	if(ifMagicSq(a,4)==1)
		puts("The given square is a magic square");
	else
		puts("The given square is not a magic square");
	return(0);
}

int ifMagicSq(int *a,int order)
{
	int i,j,flag,sum,checksum;

	/*initilise checksum to sum of principal diagonal*/	
	for(i=0,checksum=0;i<order;i++)
		checksum=checksum+*((int *)(a+i+i));

	/*check for other diagonal*/
	for(i=order-1,j=0,sum=0;i>=0;i--,j++)
		sum=sum+*((int *)(a+j+i));
	if(sum!=checksum)
		return(0);
		
	/*check for rows*/
	for(i=0;i<order;i++)
	{
		for(j=0,sum=0;j<order;j++)
			sum=*((int *)(a+i+j))+sum;
		if(sum!=checksum)
			return(0);
	}
	
	/*check for columns*/
	for(i=0;i<order;i++)
	{
		for(j=0,sum=0;j<order;j++)
			sum=*((int *)(a+j+i))+sum;
		if(sum!=checksum)
			return(0);
	}
	
	/*if control reaches to this point, it is a magic square*/
	return(1);
}