矩阵问题——蛇形矩阵

#include<stdio.h>
#include<string.h>
#define maxn 20

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-1; x++)
    {
        for(y=0; y<=n-1; y++)
            printf("%3d",a[x][y]);
        printf("\n");
    }
    return 0;
}