/**
  * Point Cloud Segmentation using Felzenszwalb-Huttenlocher Algorithm
  *
  * Copyright (C) Jacobs University Bremen
  *
  * Released under the GPL version 3.
  *
  * @author Mihai-Cotizo Sima
  */


#include <segmentation/disjoint-set.h>

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--;
}