Function kth_perm

Number Theory/Factoradic Number System.cpp:40–42

returns the k-th lexicographically smallest permutation of size n 0-th permutation is the unit permutation i.e. 0, 1, 2, .... n-1

// returns the k-th lexicographically smallest permutation of size n
// 0-th permutation is the unit permutation i.e. 0, 1, 2, .... n-1
vector<int> kth_perm(int n, int k) { // k < n!
  return get_perm(n, decimal_to_factoradic(k));
}
vector<int> factoradic_order(vector<int> p) {
  o_set<int> se;
  int n = p.size();