新学DFS，将以前暴力过的题重过，结果连模板题都过不了（QWQ

# include<bits/stdc++.h>
using namespace std;
int n, a[10], book[10];
void dfs(int step){
	if(step == n){
		for(int i = 1; i <= n; i++)
		    cout << setw(5) << a[i];
        cout << endl;
		return;
	}
	for(int i = step + 1; i <= n; i++){
		if(book[i]){
			a[i] = i;
			book[i] = 1;
		    dfs(step + 1);
		    book[i] = 0;
		} 
	}
}
int main(){
	cin >> n;
	dfs(0);
	return 0;
}