structure/union-find/union-find-undo.hpp

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• Last update: 2024-04-24 02:34:04+09:00
• Include: #include "structure/union-find/union-find-undo.hpp"

Code

struct UnionFindUndo {
  vector< int > data;
  stack< pair< int, int > > history;

  UnionFindUndo(int sz) {
    data.assign(sz, -1);
  }

  bool unite(int x, int y) {
    x = find(x), y = find(y);
    history.emplace(x, data[x]);
    history.emplace(y, data[y]);
    if(x == y) return (false);
    if(data[x] > data[y]) swap(x, y);
    data[x] += data[y];
    data[y] = x;
    return (true);
  }

  int find(int k) {
    if(data[k] < 0) return (k);
    return (find(data[k]));
  }

  int size(int k) {
    return (-data[find(k)]);
  }

  void undo() {
    data[history.top().first] = history.top().second;
    history.pop();
    data[history.top().first] = history.top().second;
    history.pop();
  }

  void snapshot() {
    while(history.size()) history.pop();
  }

  void rollback() {
    while(history.size()) undo();
  }
};

#line 1 "structure/union-find/union-find-undo.hpp"
struct UnionFindUndo {
  vector< int > data;
  stack< pair< int, int > > history;

  UnionFindUndo(int sz) {
    data.assign(sz, -1);
  }

  bool unite(int x, int y) {
    x = find(x), y = find(y);
    history.emplace(x, data[x]);
    history.emplace(y, data[y]);
    if(x == y) return (false);
    if(data[x] > data[y]) swap(x, y);
    data[x] += data[y];
    data[y] = x;
    return (true);
  }

  int find(int k) {
    if(data[k] < 0) return (k);
    return (find(data[k]));
  }

  int size(int k) {
    return (-data[find(k)]);
  }

  void undo() {
    data[history.top().first] = history.top().second;
    history.pop();
    data[history.top().first] = history.top().second;
    history.pop();
  }

  void snapshot() {
    while(history.size()) history.pop();
  }

  void rollback() {
    while(history.size()) undo();
  }
};

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