蛇形填数

//
//  main.cpp
//  c++prime
//
//  Created by SJCHEN on 2019/1/19.
//  Copyright © 2019 SJCHEN. All rights reserved.
//

#include <iostream>
#include <cstdio>
using namespace std;
#define MAXN 10
int a[MAXN][MAXN];

int main()
{
    int n,x,y,tot = 0;
    cin >> 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;//下
        while (y-1 >= 0 && !a[x][y-1]) a[x][--y] = ++tot;//左
        while (x-1 >= 0 && !a[x-1][y]) a[--x][y] = ++tot;//上
        while (y+1 < n && !a[x][y+1]) a[x][++y] = ++tot;//右
    }
    for (x = 0; x < n; x++) {
        for (y = 0; y < n; y++)
            printf("%3d",a[x][y]);
        cout << endl;
    }
    return 0;
}