NOIP 2015 神奇的幻方

#include<bits/stdc++.h>
using namespace std;
int n,a[40][40],x,y;
int main(){
	cin>>n;
	x=1,y=(n+1)/2;
	for(int i=1;i<=n*n;i++){
		a[x][y]=i;
		if(!a[(x-2+n)%n+1][y%n+1]) 
		    x=(x-2+n)%n+1,y=y%n+1;
		else x=x%n+1;
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++)
		    cout<<a[i][j];
		cout<<endl;
	}
	return 0;
}