Thread: help with magic square

/blinks

Code:

#include <iostream>
#include <vector>

using namespace std;

void OddMagicSquare(vector<vector<int> > &matrix, int n);
void DoublyEvenMagicSquare(vector<vector<int> > &matrix, int n);
void SinglyEvenMagicSquare(vector<vector<int> > &matrix, int n);
void MagicSquare(vector<vector<int> > &matrix, int n);
void PrintMagicSquare(vector<vector<int> > &matrix, int n);

int main(int argc, char* argv[])
{
	int n;
	printf("Enter order of square: ");
	scanf("%d", &n);

	vector<vector<int> > matrix(n, vector<int> (n, 0));

	if (n<3)
	{
		printf("\nError: n must be greater than 2\n\n");
		return -1;
	}

	MagicSquare(matrix, n);  

	//Print results
	PrintMagicSquare(matrix, n);

	return 0;
}

void MagicSquare(vector<vector<int> > &matrix,int n)
{
	if (n%2==1)        //n is Odd
		OddMagicSquare(matrix, n);
	else          //n is even
		if (n%4==0)    //doubly even order
			DoublyEvenMagicSquare(matrix, n);
		else      //singly even order
			SinglyEvenMagicSquare(matrix, n);
}

void OddMagicSquare(vector<vector<int> > &matrix, int n)
{
	int nsqr = n * n;
	int i=0, j=n/2;     // start position

	for (int k=1; k<=nsqr; ++k) 
	{
		matrix[i][j] = k;

		i--;
		j++;

		if (k%n == 0) 
		{ 
			i += 2; 
			--j; 
		}
		else 
		{
			if (j==n) 
				j -= n;
			else if (i<0) 
				i += n;
		}
	}
}

void DoublyEvenMagicSquare(vector<vector<int> > &matrix, int n)
{
	vector<vector<int> > I(n, vector<int> (n, 0));
	vector<vector<int> > J(n, vector<int> (n, 0));

	int i, j;

	//prepare I, J
	int index=1;
	for (i=0; i<n; i++)
		for (j=0; j<n; j++)
		{
			I[i][j]=((i+1)%4)/2;
			J[j][i]=((i+1)%4)/2;
			matrix[i][j]=index;
			index++;
		}

		for (i=0; i<n; i++)
			for (j=0; j<n; j++)
			{
				if (I[i][j]==J[i][j])
					matrix[i][j]=n*n+1-matrix[i][j];
			}
}

void SinglyEvenMagicSquare(vector<vector<int> > &matrix, int n)
{
	int p=n/2;

	vector<vector<int> > M(p, vector<int> (p, 0));
	MagicSquare(M, p);

	int i, j, k;

	for (i=0; i<p; i++)
		for (j=0; j<p; j++)
		{
			matrix[i][j]=M[i][j];
			matrix[i+p][j]=M[i][j]+3*p*p;
			matrix[i][j+p]=M[i][j]+2*p*p;
			matrix[i+p][j+p]=M[i][j]+p*p;
		}

		if (n==2)
			return;  

		vector<int> I(p, 0);
		vector<int> J;

		for (i=0; i<p; i++)
			I[i]=i+1;

		k=(n-2)/4;

		for (i=1; i<=k; i++)
			J.push_back(i);

		for (i=n-k+2; i<=n; i++)
			J.push_back(i);

		int temp;
		for (i=1; i<=p; i++)
			for (j=1; j<=J.size(); j++)
			{
				temp=matrix[i-1][J[j-1]-1];
				matrix[i-1][J[j-1]-1]=matrix[i+p-1][J[j-1]-1];
				matrix[i+p-1][J[j-1]-1]=temp;
			}

			//j=1, i
			//i=k+1, k+1+p
			i=k; 
			j=0;
			temp=matrix[i][j]; matrix[i][j]=matrix[i+p][j]; matrix[i+p][j]=temp;

			j=i;
			temp=matrix[i+p][j]; matrix[i+p][j]=matrix[i][j]; matrix[i][j]=temp;
}


void PrintMagicSquare(vector<vector<int> > &matrix, int n)
{
	for (int i=0; i<n; i++) 
	{
		for (int j=0; j<n; j++)
			printf(" %3d", matrix[i][j]);

		printf("\n");
	}

	printf("\n\n");
}