Problem:
Permutation Enumeration

For given an integer $n$, print all permutations of $\{1, 2, ..., n\}$ in lexicographic order.

Input

An integer $n$ is given in a line.

Output

Print each permutation in a line in order. Separate adjacency elements by a space character.

Constraints

$1 \leq n \leq 9$

Sample Input 1

2

Sample Output 1

1 2
2 1

Sample Input 2

3

Sample Output 2

1 2 3
1 3 2
2 1 3
2 3 1
3 1 2
3 2 1

Solution in C++14 (judge verdict: Accepted)

#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
using namespace std;
using Int = long long;
using ll = long long;
using Double = long double;
const Int INF = 1LL<<55;
const Int mod = (1e9)+7;
using P = pair<Int,Int>;
using T = tuple<Int,Int,Int>;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
ostream& operator<<(ostream& o,P p){return o<<"("<<p.first<<","<<p.second<<")";}
ostream& operator<<(ostream& o,T t){return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
istream& operator>>(istream& i,P &p){return i>>p.first>>p.second;}
ostream& operator<<(ostream& o,vector<auto> &a){Int i=0;for(auto t:a)o<<(i++?" ":"")<<t;return o;}
istream& operator>>(istream& i,vector<auto> &a){for(auto &t:a)i>>t;return i;}
void prArr(auto a,string s=" "){Int i=0;for(auto t:a)cout<<(i++?s:"")<<t;cout<<endl;}


signed main(){
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  int n;
  cin>>n;
  vector<int> A(n); iota(A.begin(), A.end(), 1);
  do{
    cout<<A<<endl;
  }while(next_permutation(A.begin(), A.end()));

  
  
  return 0;
}