蛇形填数

#include<stdio.h>
#include<string.h>
#define MAXN 10
int a[MAXN][MAXN];
int main()
{
    int n, x, y, tot = 0;
    scanf("%d",&n);
    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]);
          printf("\n");
    }
    return 0;
}