Persistent-Union-Find(永続Union-Find) (structure/union-find/persistent-union-find.hpp)

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• Last update: 2024-05-01 23:44:47+09:00
• Include: #include "structure/union-find/persistent-union-find.hpp"

Verified with

• test/verify/yosupo-persistent-unionfind.test.cpp

Code

/*
 * @brief Persistent-Union-Find(永続Union-Find)
 */
struct PersistentUnionFind {
  PersistentArray<int, 3> data;

  PersistentUnionFind() {}

  PersistentUnionFind(int sz) { data.build(vector<int>(sz, -1)); }

  int find(int k) {
    int p = data.get(k);
    return p >= 0 ? find(p) : k;
  }

  int size(int k) { return (-data.get(find(k))); }

  bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return false;
    auto u = data.get(x);
    auto v = data.get(y);

    if (u < v) {
      auto a = data.mutable_get(x);
      *a += v;
      auto b = data.mutable_get(y);
      *b = x;
    } else {
      auto a = data.mutable_get(y);
      *a += u;
      auto b = data.mutable_get(x);
      *b = y;
    }
    return true;
  }
};

#line 1 "structure/union-find/persistent-union-find.hpp"
/*
 * @brief Persistent-Union-Find(永続Union-Find)
 */
struct PersistentUnionFind {
  PersistentArray<int, 3> data;

  PersistentUnionFind() {}

  PersistentUnionFind(int sz) { data.build(vector<int>(sz, -1)); }

  int find(int k) {
    int p = data.get(k);
    return p >= 0 ? find(p) : k;
  }

  int size(int k) { return (-data.get(find(k))); }

  bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return false;
    auto u = data.get(x);
    auto v = data.get(y);

    if (u < v) {
      auto a = data.mutable_get(x);
      *a += v;
      auto b = data.mutable_get(y);
      *b = x;
    } else {
      auto a = data.mutable_get(y);
      *a += u;
      auto b = data.mutable_get(x);
      *b = y;
    }
    return true;
  }
};

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