#include<bits/stdc++.h> using namespace std; int a[10]; int book[10]; void dfs(int step){ if(step==4){ for(int i=1;i<=3;i++) cout<<a[i]<<" "; cout<<endl; return; } for(int i=1;i<=3;i++){ if(book[i]==0){ a[step]=i; book[i]=1; dfs(step+1); book[i]=0; } } } int main(){ dfs(1); return 0; }