打印螺旋矩陣

#include<stdio.h>
#define MAX_LEN 20
void main()
{
	int i,j,k,m,a,n,N;
	int num[MAX_LEN][MAX_LEN];
	scanf("%d",&N);
	num[1][0] = 0;
	for(i=1,n=N;i<=(N+1)/2;i++,n--){
		for(j=i;j<=n;j++)
			num[i][j] = num[i][j-1]+1;
		for(k=i;k<n;k++)
			num[k+1][n] = num[k][n]+1;
		for(m=n-1;m>=i;m--)
			num[n][m] = num[n][m+1]+1;
		for(a=n-1;a>i;a--)
			num[a][i] = num[a+1][i]+1;
	}
	for(i=1;i<=N;i++){
		for(j=1;j<=N;j++){
			printf("%d ",num[i][j]);
		}			
		printf("\n");
	}
}