Data Structures (Weiss) Chapter 8: Union and Find, Disjoint Sets, union by sizes, C++

//

//  main.cpp

//  Data Structure TRY1

//

//  Created by zr9558 on 6/7/13.

//  Copyright (c) 2013 zr9558. All rights reserved.

//

// Data Structure C++, Weiss, P.319 Disjoint set class

// do the union of the set like the form {0,1,2,...,n} where n is an integer.

// union by sizes

#include <iostream>

using namespace std;

#include <vector>

class DisjSets

{

public:

    DisjSets(int numElements);

    

   int find( int x)const;

   int find( int x);

   void unionSets( int root1,int root2);

    

private:

   vector<int> s;

    

};

DisjSets::DisjSets(int numElements): s(numElements)

{

   for( int i=0; i<s.size(); ++i)

       s[i]=-1;

}

intDisjSets::find( int x)const

{

    if(s[x]<0)return x;  // s[x]==-1 denotes, x is the root of the set.

    elsereturn find(s[x]);// find the root of x

}

intDisjSets::find( int x)

{

   if( s[x]<0)

       return x;

   else

       return s[x]=find(s[x]);

}

// union by sizes

voidDisjSets::unionSets( int root1, int root2)

{

   if( s[root1]>=s[root2])

    {

       s[root2]+=s[root1];

       s[root1]=root2;

    }

   else

    {

       s[root1]+=s[root2];

       s[root2]=root1;

    }

}

int main()

{

    

    

    

    

    

    

    

    return 0;

}