求奇偶阶幻方

奇：

hdoj 1998 奇数阶魔方 

#include <iostream>
#include <cstring>
using namespace std;

int num[20][20];


void f(int x, int y, int n) {
    int x1, y1, i, j;
    /*
    for(i=0; i<n; ++i) {
        for(j=0; j<n; ++j) {
            printf("%4d", num[i][j]);
        }
        printf("\n");
    }
    printf("\n\n");*/
    if(num[x][y] == n*n) return;
    x1 = x - 1;
    y1 = y + 1;
    if(y1 >= n && x1 >= 0 && x1 < n) y1 = 0;
    else if(x1 < 0 && y1 >= 0 && y1 < n) x1 = n - 1;
    else if(x1 == -1 && y1 == n) x1 = 1, y1 = n-1;
    else if(num[x1][y1] != 0) x1 = x+1, y1 = y;
    num[x1][y1] = num[x][y] + 1;
    f(x1, y1, n);
}



void solve(int n) {
    int x, y, x1, y1, i, j;
    memset(num, 0, sizeof(num));
    num[0][n/2] = 1;
    num[n-1][n/2] = n * n;
    num[n-1][n/2+1] = 2;
    x = n-1;
    y = n/2 + 1;
    
    f(x, y, n);

    for(i=0; i<n; ++i) {
        for(j=0; j<n; ++j) {
            printf("%4d", num[i][j]);
        }
        printf("\n");
    }
}
    
    

int main() {
//    freopen("c:/aaa.txt", "r", stdin);
    int n, T;
    scanf("%d", &T);
    while(T --) {
        scanf("%d", &n);
        solve(n);
    }
    return 0;
}

 另外求偶数阶幻方：（网上找的代码）

#include<iostream>
#include<iomanip>
using namespace std;

#define max 179
int a[max][max];//幻方的格
int k, i, j;
int n;//幻方的阶
int sum;//每行的和

void check()
{
	int temp1, temp2;
	//row and column check
	for( i = 1 ; i <= n; i ++ )
	{
		temp1 = 0;
		temp2 = 0;
		for( j = 1 ; j <= n; j ++ )
		{
			temp1 += a[i][j];
			temp2 += a[j][i];
		}
		if( temp1 != sum || temp2 != sum )
		{
			cout<<"check error"<<endl;
			return;
		}
	}
	//cross check
	temp1 = 0;
	temp2 = 0;
	for( i = 1 ; i <= n; i ++ )
	{
		temp1 += a[i][i];
		temp2 += a[i][n-i+1];
	}
	if( temp1 != sum || temp2 != sum )
	{
		cout<<"check error"<<endl;
		return;
	}
	cout<<"check passed"<<endl;
	
}



void swap( int & a , int & b )
{
	int t;
	t = a; a = b; b = t;
}




int main()
{
	while(1)
	{
		cout<<"input the order of magic(even) n = ";
		cin>>n;
		
		if( n % 2 == 1 )
		{
			cout<<"input error"<<endl;
			continue;
		}
		sum = n*(n*n+1)/2;
		cout<<"sum of a line: "<<sum<<endl;
		
		for( i = 1 ; i <= n ; i ++ )
		{
			for( j = 1 ; j <= n ; j ++ )
			{
				a[i][j] = (i - 1) * n + j;
			}
		}

		k = n / 4;
		if( n == 4 * k ) // n是4的倍数
		{
			for( i = k + 1 ; i <= 3 * k ; i ++ )
			{
				for( j = 1 ; j <= k ; j ++ )
				{
					swap(a[i][j],a[n+1-i][n+1-j]);
					swap(a[j][i],a[n+1-j][n+1-i]);
				}
			}
		}
		else // n = 4 * k + 2
		{
			for( i = 1 ; i <= 2 * k + 1; i ++ )
			{
				swap(a[i][i],a[n+1-i][n+1-i]);
				swap(a[i][n+1-i],a[n+1-i][i]);   
			}
			for( i = 1 ; i <= k + 2 ; i ++ )
			{
				for( j = k + 3 ; j <= 3 * k ; j ++ )
				{
					swap(a[i][j],a[n+1-i][j]);
					swap(a[j][i],a[j][n+1-i]);
				}
			}
			for( i = k + 3 ; i <= 2 * k + 1 ; i ++ )
			{
				for( j = 1 ; j <= k - 1 ; j ++ )
				{
					swap(a[i][j],a[n+1-i][j]);
					swap(a[i][n+1-j],a[n+1-i][n+1-j]);
					swap(a[j][i],a[j][n+1-i]);
					swap(a[n+1-j][i],a[n+1-j][n+1-i]);
				}
			}
			for( i = 1 ; i <= k * 2 + 1 ; i ++ )
			{
				if( i == 1 ) j = k + 2;
				else j = i - 1;
				swap(a[i][j],a[n+1-i][j]);
				swap(a[j][i],a[j][n+1-i]);
				
			}
		}
		//output
		for( i = 1 ; i <= n ; i ++ )
		{
			for( j = 1 ; j <= n ; j ++ )
			{
				cout<<setw(4)<<a[i][j];
			}
			cout<<endl;
		}
		check();//检查是否满足幻方条件
	}
	return 0;
}