题解

#include <iostream>
#include <vector>
using namespace std;
bool board[20][20];
vector<vector<int> > ans;
vector<int> path;
int n;
bool is_valid(int x,int y){
	for(int i = 1;i < x;i++){
		if(board[i][y]) return false;
		if(x - i >= 1 && y - i >= 1 && board[x - i][y - i]) return false;
		if(x - i >= 1 && y + i <= n && board[x - i][y + i]) return false;
	}
	return true;
}
void dfs(int now){
	if(now == n + 1){
		ans.push_back(path);
		return ;
	}
	for(int i = 1;i <= n;i++){
		if(!is_valid(now,i)) continue;
		board[now][i] = true;
		path.push_back(i);
		dfs(now + 1);
		board[now][i] = false;
		path.pop_back();
	}
}
int main(){
	cin >> n;
	dfs(1);
	for(int i = 0;i < 3;i++){
		for(int j = 0;j < n;j++) cout << ans[i][j] << " ";
		cout << endl;
	}
	cout << ans.size() << endl;
	return 0;
}