cpp-flashcards/org/cpp/dsa/udfs.org

Udfs

• impl

impl

#include <vector>
#include <numeric>
#include <algorithm>
class Ufs {
  private:
  std::vector<int> p;
  std::vector<int> s;
  std::vector<int> r;
  public:
  Ufds(int n) {
    p.resize(n);
    std::iota(p.begin(), p.end(), 0);
    s.assign(n, 1); // test on equality with the assign fill and iota explain the difference
    std::fill(r.begin(),r.end(),0);
    numSets = n;
  }
  ~Ufds() {}
  ~Ufds() = default;
  int find(int x) {
    if (p[x] == x) return x;
    return p[x] = find(p[x]);
  }
  int find(int x) {
    int px = p[x];
    if (px != x) {
      px = find(px);
    }
    p[x] = px;
    return px;
  }
};

should ask what new returns? delete? what happens? why are we deleting it ? heap allocated? should show equivalent version of using std::array to vector should ask what resize does?

what about a true dynammic version where we create it upon calling find()