蛇形填数

#include<stdio.h>
#include<string.h>
#define MAX 10

int a[MAX][MAX];
int main()
{
    int n,x,y,tot=0;
    while(scanf("%d",&n)!=EOF)
    {
        memset(a,0,sizeof(a));
        tot=a[x=0][y=n-1]=1;
        while(tot<n*n)
        {
            while(x+1<n &&!a[x+1][y])   a[++x][y] = ++tot;
            while(y-1>=0 && !a[x][y-1]) a[x][--y] = ++tot;
            while(x-1>=0 && !a[x-1][y]) a[--x][y] = ++tot;
            while(y+1<n && !a[x][y+1])  a[x][++y] = ++tot;
        }
        for(x=0;x<n;x++)
        {
            for(y=0;y<n;y++)
            {
                printf("%3d",a[x][y]);
            }
            putchar('\n');
        }
    }
    return 0;
}