mxUnionFind (mxGraph 4.2.1 API Specification)

java.lang.Object
- com.mxgraph.analysis.mxUnionFind

```
public class mxUnionFind
extends java.lang.Object
```
Implements a union find structure that uses union by rank and path compression. The union by rank guarantees worst case find time of O(log N), while Tarjan shows that in combination with path compression (halving) the average time for an arbitrary sequence of m >= n operations is O(m*alpha(m,n)), where alpha is the inverse of the Ackermann function, defined as follows: alpha(m,n) = min{i >= 1 | A(i, floor(m/n)) > log n} for m >= n >= 1 Which yields almost constant time for each individual operation.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

class mxUnionFind.Node
A class that defines the identity of a set.

Field Summary

Fields
Modifier and Type Field Description

protected java.util.Map<java.lang.Object,mxUnionFind.Node> nodes
Maps from elements to nodes

Constructor Summary

Constructors
Constructor Description

mxUnionFind(java.lang.Object[] elements)
Constructs a union find structure and initializes it with the specified elements.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`differ(java.lang.Object a, java.lang.Object b)`	Returns true if element a and element b are not in the same set.
`mxUnionFind.Node`	`find(mxUnionFind.Node node)`	Returns the set that contains `node`.
`mxUnionFind.Node`	`getNode(java.lang.Object element)`	Returns the node that represents element.
`void`	`union(mxUnionFind.Node a, mxUnionFind.Node b)`	Unifies the sets `a` and `b` in constant time using a union by rank on the tree size.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - nodes
```
protected java.util.Map<java.lang.Object,mxUnionFind.Node> nodes
```
    Maps from elements to nodes
- Constructor Detail
  - mxUnionFind
```
public mxUnionFind(java.lang.Object[] elements)
```
    Constructs a union find structure and initializes it with the specified elements.
    
    Parameters:
    
    elements -
- Method Detail
  - getNode
```
public mxUnionFind.Node getNode(java.lang.Object element)
```
    Returns the node that represents element.
  - find
```
public mxUnionFind.Node find(mxUnionFind.Node node)
```
    Returns the set that contains node. This implementation provides path compression by halving.
  - union
```
public void union(mxUnionFind.Node a,
                  mxUnionFind.Node b)
```
    Unifies the sets a and b in constant time using a union by rank on the tree size.
  - differ
```
public boolean differ(java.lang.Object a,
                      java.lang.Object b)
```
    Returns true if element a and element b are not in the same set. This uses getNode and then find to determine the elements set.
    
    Parameters:
    
    a - The first element to compare.
    
    b - The second element to compare.
    
    Returns:
    
    Returns true if a and b are in the same set.
    
    See Also:
    
    getNode(Object)