#include<bits/stdc++.h>
using namespace std;
int n;
vector<int> a[100];
int u=1,x=1,y=1;
void f(int g,int x,int y){
	if(a[x][y+1]!=0&&a[x][y-1]!=0&&a[x+1][y]!=0&&a[x-1][y]!=0) return ;
	if(x==n+1||a[x+1][y]!=0) u=2;
	else if(y==n+1||a[x][y+1]!=0) u=3;
	else if(x<=0||a[x-1][y]!=0) u=4;
	else if(y<=0||a[x][y-1]!=0) u=1;
	if(u==1){
		a[x][y]=g;
		cout<<" "<<g;
		x++;
		f(g+1,x,y);
	}
	else if(u==2){
		a[x][y]=g;
		cout<<" "<<g;
		y++;
		f(g+1,x,y);
	}
	else if(u==3){
		a[x][y]=g;
		cout<<" "<<g;
		x--;
		f(g+1,x,y);
	}
	else if(u==4){
		a[x][y]=g;
		cout<<" "<<g;
		y--;
		f(g+1,x,y);
	}
}
int main(){
	cin>>n;
	f(1,1,1);
	return 0;
}

啥也不是，蛇形方阵（半成品）

what the f?

666

666