#define SIZE  160              /* Consider a memory for increasing the size. */

#include "stdio.h"
#include "stdlib.h"
#include "conio.h"

int m[SIZE][SIZE];

void odd_num(int n);
void even_num(int n);
void output(int n);
void _swap(int i1, int j1, int i2, int j2);

main()
{
    int i,j,n;
    char *s="           ";

    printf("\n***************************************************************************");
    printf("\n*                     <  < <   MAGIC  SQUARE   > >  >                     *");
    printf("\n*            by;  Kwon Young Shin(brainstm@chollian.net)                  *");
    printf("\n***************************************************************************");

    while( 1 ) {
        printf("\n\n\n:-) Input the number(3-%d): ",SIZE);
        gets(s);
        n=atoi(s);
            if(n <  3  || n > SIZE) break;
        if(n% 2 ) odd_num(n);
        else even_num(n);
        output(n);
    }

    printf("\n\n* .. Quit .. .  [[ <   MAGIC  SQUARE   > ]]  . .. *\n\n\n");
}

void odd_num(int n)
{
    int i,j,num= 1 ;
    int nn=n* 3 / 2 ;

    for(i= 0 ; i < n; i++)
        for(j= 0 ; j < n; j++)
            m[(j-i+nn)%n][(i* 2 -j+n)%n]=num++;
}

void even_num(int n)
{
    int i,j,num= 1 ;
    int nminus=n- 1 ,nmiddle=n/ 2 ,nn=n*n+ 1 ;
    int osl= 0 ;
    int switch_row[ 2 ];
    int last_switch_column;
    int first_block=(n- 2 )/ 4 ,second_block=nminus-first_block;
    int first_inside=n/ 4 ,second_inside=nminus-first_inside;

    for(j= 0 ; j < n; j++)
        for(i= 0 ; i < n; i++) {
            if(i >= first_inside && i <= second_inside && j >= first_inside && j <= second_inside)
                m[i][j]=num;
            else if((i > first_block && i < second_block) || (j > first_block && j < second_block))
                m[i][j]=nn-num;
            else m[i][j]=num;
            num++;
        }
    if(!(n% 4 )) return;

    switch_row[ 0 ]=random(nmiddle- 1 )+first_block+ 1 ;
    switch_row[ 1 ]=random(nmiddle- 1 );
    if(switch_row[ 1 ] >= first_block) switch_row[ 1 ]+=(nmiddle+ 1 );
    last_switch_column=random(nmiddle- 1 );
    if(last_switch_column >= first_block) last_switch_column+=(nmiddle+ 1 );

/* Simply, you can write as follows.. 
    switch_row[0]=nmiddle;
    switch_row[1]=0;
    last_switch_column=0;
*/

    for(i= 0 ; i < nmiddle; i++) {
        if(i==first_block || i==second_block) {
            osl= 1 -osl;
            continue;
        }
        _swap(second_block, i, second_block, nminus-i);
        _swap(i, first_block, nminus-i, first_block);
        _swap(i, second_block, nminus-i, second_block);
        _swap(i, switch_row[osl], nminus-i, switch_row[osl]);
    }
    for(i=first_block+ 1 ; i < second_block; i++) {
        _swap(first_block, i, second_block, i);
        _swap(i, first_block, i, second_block);
    }
    _swap(first_block, nmiddle, second_block, nmiddle);
    _swap(last_switch_column, first_block, last_switch_column, second_block);
}

void output(int n)
{
    int i,j,ch,err= 0 ;
    unsigned long sum,sl,sc,sd1= 0 ,sd2= 0 ;

    sum=(unsigned long)n*(n*n+ 1 )/ 2 ;
    printf(";-) SUM = %lu.     * ..check sum... .  .    ",sum);
    for(j= 0 ; j < n; j++) {
        sd1+=m[j][j];
        sd2+=m[j][n-j- 1 ];
        sl= 0 ;
        sc= 0 ;
        for(i= 0 ; i < n; i++) {
            sl+=m[i][j];
            sc+=m[j][i];
        }
        if(sl!=sum) {
            err++;
            printf("\n> Sum of the row-(%d) is %lu. It's incorrect..",j+1,sl);
        }
        if(sc!=sum) {
            err++;
            printf("\n> Sum of the column-(%d) is %lu. It's incorrect..",j+ 1 ,sc);
        }
    }
    if(sd1!=sum) {
        err++;
        printf("\n> Sum of the diagonal-(\\) is %lu. It's incorrect..",j+1,sd1);
    }
    if(sd2!=sum) {
        err++;
        printf("\n> Sum of the diagonal-(/) is %lu. It's incorrect..",j+ 1 ,sd2);
    }
    if(err) printf("\n\n* %d errors are happened.",err);
    else printf("- O.K. -");
    printf("\n\n:-? Do you want to display(Y/n)? ");
    ch=getch();
    if(ch=='n' || ch=='N') return;
    printf("\n---+---------------------------------------------------------------------------");
    for(j= 0 ; j < n; j++) {
        printf("\n%2d)] ",j+ 1 );
        for(i= 0 ; i < n; i++)
            printf("%4d,",m[i][j]);
    }
    printf("\n---+---------------------------------------------------------------------------");
}

void _swap(int i1, int j1, int i2, int j2)
{
    int k;

    k=m[i1][j1];
    m[i1][j1]=m[i2][j2];
    m[i2][j2]=k;
}