www.pudn.com > CVPR12_SAS_code.zip > disjoint-set.h, change:2006-12-28,size:1857b


/* 
Copyright (C) 2006 Pedro Felzenszwalb 
 
This program is free software; you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation; either version 2 of the License, or 
(at your option) any later version. 
 
This program is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
GNU General Public License for more details. 
 
You should have received a copy of the GNU General Public License 
along with this program; if not, write to the Free Software 
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA 
*/ 
 
#ifndef DISJOINT_SET 
#define DISJOINT_SET 
 
// disjoint-set forests using union-by-rank and path compression (sort of). 
 
typedef struct { 
  int rank; 
  int p; 
  int size; 
} uni_elt; 
 
class universe { 
public: 
  universe(int elements); 
  ~universe(); 
  int find(int x);   
  void join(int x, int y); 
  int size(int x) const { return elts[x].size; } 
  int num_sets() const { return num; } 
 
private: 
  uni_elt *elts; 
  int num; 
}; 
 
universe::universe(int elements) { 
  elts = new uni_elt[elements]; 
  num = elements; 
  for (int i = 0; i < elements; i++) { 
    elts[i].rank = 0; 
    elts[i].size = 1; 
    elts[i].p = i; 
  } 
} 
   
universe::~universe() { 
  delete [] elts; 
} 
 
int universe::find(int x) { 
  int y = x; 
  while (y != elts[y].p) 
    y = elts[y].p; 
  elts[x].p = y; 
  return y; 
} 
 
void universe::join(int x, int y) { 
  if (elts[x].rank > elts[y].rank) { 
    elts[y].p = x; 
    elts[x].size += elts[y].size; 
  } else { 
    elts[x].p = y; 
    elts[y].size += elts[x].size; 
    if (elts[x].rank == elts[y].rank) 
      elts[y].rank++; 
  } 
  num--; 
} 
 
#endif