# Disjoint Sets

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• 11-29-2002
roberto81
HOW WOULD I IMPLEMENT IT HERE

class Point
{
public:
Point(): x(0),y(0),value(-1),index(0) PARENT(NULL){}
Point(int xCoordinate, // x coordinate in (x,y)
int yCoordinate // y coordinate in (x,y)
): x(xCoordinate), y(yCoordinate),value(-1),index(0),PARENT(NULL) {}
Point(const Point & rhs): x(rhs.x), y(rhs.y), index(rhs.index),
value(rhs.value) PARENT->RHS->PARENT{}//Copy Constructor

Point & operator =(const Point & rhs);

POINT * PARENT;
int x;
int y;

int index; //place label
int value; //value inside place label
};

iS THIS THE RIGHT WAY
• 11-29-2002
Nick
I would go with

Code:

```class Point { public:       int x;       int y;       Point* parent;       Point(int newX, int newY) : x(newX), y(newY) {               parent = NULL;       } private:       // define private since we shouldn't have to call them       Point& operator=(Point& left, Point& right);       Point(const Point&); };```
• 11-29-2002
roberto81
thanks i will check that out and talk to you tommorrow thanks
• 11-29-2002
roberto81
How would i do union by size with parent

i would have to do parent->point.value = negative what ever right
• 11-30-2002
roberto81
nick when i create does functions there is conflict because we are use a pointer with a reference

Code:

```Point* DisjSets::findPathcompression( Point & a ) {     if( a.parent  == NULL)           return &a;     else           return a.parent = findPathcompression(a.parent); }```
i still can get it to work correctly my union sets is wrong

my union set by size is
Code:

```                void DisjSets::unionSets( Point & a, Point & b )         {             int indexA = findPathcompression(a);                         int indexB = findPathcompression(b);                         if(s[indexA].value < s[indexB].value ||                                 s[indexA].value == s[indexB].value)                         {                                 s[indexA].value += s[indexB].value;                                 s[b.index].value = s[indexA].index;                         }                         else                         {                                 s[indexB].value += s[indexA].value;                                         s[a.index].value = s[indexB].index;                         } }```
i made the path compression send an int out

Code:

```                int DisjSets::findPathcompression( Point & a )         {             if( a.value < 0 )                 return a.index;             else                 return s[a.index].value = findPathcompression(s[a.value]);         }```
my = operator is correct
Code:

``` Point& Point::operator =(const Point & rhs) {                 rhs.value = index;         return *this; }```
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