Output some values in special format - c

Question

I'm trying to solve some problems. but there is something wrong with my code.
The problem is : Given a number n, output n*n in the following format.
Input:
n=3
Output:
7 8 1
6 9 2
5 4 3
Here is my code: (I know there are some bugs in it, but I can't fix it. If you have better ideas, help me.)
Thank in advance.
#include<stdio.h>
#include<stdlib.h>
void oput(int **matrix,int n);
int main()
{ int x=0,y=0,n,k=1;
scanf("%d",&n);
int **matrix = malloc(sizeof(int)*n*n);
if(matrix==NULL)
{
perror("can't allocate");
return 1;
}
//Input values to x*y matrix
while(n>=1)
{
for(x=0,y=n-1;x<n;x++)
{
matrix[x][y]=k++;
}
for(x=n-1,y=n-1;y>=0;y--)
{
matrix[x][y]=k++;
}
for(x=n-1,y=0;x>=0;x--)
{
matrix[x][y]=k++;
}
n--;
}
oput(matrix,n);
free(matrix);
return 0;
}
//output values by row.
void oput(int **matrix,int n)
{
int i=0,j=0;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
printf("%d ",matrix[i][j]);
}
printf("\n");
}
}
Error arises at running time.

Answer 1

Just for fun I worked on a solution for this problem.
I'm not allowed to write comments under the question, yet, so I assumed that starting the "spiral numbering" from the upper right corner of the matrix was a requirement of the problem.
My solution consists in adding numbers all over the perimeter, using four different loops. And then starting again adding an indentation level.
#include <stdio.h>
#include <string.h>
void printMatrix( int *nMatrix, int n, char *title )
{
int i, j;
if( title )
printf( "%s\n", title );
for( i=0; i<n; i++ )
{
for( j=0; j<n; j++ )
{
printf( "%d\t", *(nMatrix+n*i+j) );
}
printf( "\n" );
}
}
void main( int argc, char *argv[] )
{
if( argc == 2 )
{
int n = atoi ( argv[1] );
int i, j;
printf( "Input value: %d\n", n );
if( n > 0 && n <= 10 )
{
int spiral[n][n];
int indentNr, x, y, lastNr=0;
memset( spiral, 0, n*n*sizeof( int ));
/* As indentNr is incremented, inner frames are filled */
for( indentNr=0; n-2*indentNr>0; indentNr++ )
{
/* Go South */
for( x=indentNr, y=n-1-indentNr; x<n-indentNr; x++ )
{
spiral[x][y] = ++lastNr;
}
/* Go West (Village People, 1979) */
for( y=n-2-indentNr, x=n-1-indentNr; y>=indentNr; y-- )
{
spiral[x][y] = ++lastNr;
}
/* Go North */
for( x=n-2-indentNr, y=indentNr; x>=indentNr; x-- )
{
spiral[x][y] = ++lastNr;
}
/* Go East */
for( y=1+indentNr, x=indentNr; y<n-1-indentNr; y++ )
{
spiral[x][y] = ++lastNr;
}
}
/* Print results */
printMatrix( &(spiral[0][0]), n, "Final spiral:" );
}
else
{
printf( "ERROR: 'n' too big!\n" );
}
}
else
{
printf( "USAGE: spiral n\n" );
}
}
Please note that:
Input of 'n' is inserted with main argument (no scanf)
I limited 'n' to 10
This solution is iterative. I did not analyse recursive solutions
There is probably a more elegant solution for skipping all 4 loops for inner frames with n=1 and n=2. I did not spent much time in figuring it out
I tested both odd and even scenarios and both seem to work fine. I tested up to n=10. I don't expect troubles for bigger numbers (except for presentation issues in case of big numbers), but feel free to report me any bug.