#include <bits/stdc++.h>
using namespace std;
int n,k,a[20];
bool vis[20];
void dfs(int x){
	if(x==k+1){
		for(int i=1;i<=k;i++){
			cout<<a[i]<<" ";
		} 
		cout<<"\n";
		return;
	}
	for(int i=a[x-1];i<=n;i++){
		if(!vis[i]){
			vis[i]=1;
			a[x]=i;
			dfs(x+1);
			vis[i]=0;
		}
	}
}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>k;
	a[0]=1;
	dfs(1);
	return 0;
}

报错提醒：wrong answer Too short on line 1.