#include using namespace std; const int N = 110; int a[N], al, n; // 标准错误答案 void dfs(int u) { if (u == n + 1) { for (int i = 1; i <= al; i++) cout << a[i] << " "; cout << endl; return; } a[++al] = u; dfs(u + 1); al--; dfs(u + 1); } int main() { cin >> n; dfs(1); return 0; }