include[HTML_REMOVED]
using namespace std;
const int N=20;
int n;
int st[N];
void dfs(int x ){
if(x>n){
for (int i = 0; i <=n; i++)
{
if (st[i]==1)
{
printf(“%d “,i);
}
}
cout << endl;
return;
}
//不选
st[x]=2;
dfs(x+1);
st[x]=0;//恢复现场3
//选
st[x]=1;
dfs(x+1);
st[x]=0;//恢复现场
}
int main(){
scanf(“%d”,&n);
dfs(1);
return 0;
}