paste bin

#include <cstdio>
#define MAXN 50
int block[MAXN][MAXN];

void outputSquare(int W)
{
    for(int i=0;i<W;i++)
    {
        for(int j=0;j<W;j++)
        {
            printf("%d ",block[i][j]);
        }
        printf("\n");
    }
}

int main(void)
{
    int N,W;
    scanf("%d",&N);
    W=2*N-1;

    int num = 1,i,j,next_i,next_j;
    i=0;
    j=N-1;
    block[i][j]=num;
    num++;
    for(num=2;num<=W*W;num++)
    {
        next_i = i-1;
        if(next_i<0)
        {
            next_i=W-1;
        }
        next_j = j+1;
        if(next_j == W)
        {
            next_j=0;
        }
        if(block[next_i][next_j]!=0)
        {
            next_i = i+1;
            if(next_i==W)
            {
                next_i = 0;
            }            
            next_j = j;
        }
        block[next_i][next_j] = num;
        i = next_i;
        j = next_j;
    }
    outputSquare(W);

    return 0;
}