and check Set (Java implementation)

And check set: Using array to realize the idea

The number stored in the array represents the collection to which it belongs. For example, Arr[4]==1; Representative 4 is the first group. If Arr[7]==1, the Representative 7 is also the first group. Since arr[4] = = arr[7] = = 1, then the description 4 and 7 belong to a set,

Code

/** * Array Implementation and check set, the element inside the number represents the collection number */public class Unionfind {/** * array, representing and checking all elements * * private int[] ID;    /** * and check the number of elements of the set */private int size; /** * Constructs a new and checked set * * @param size Initial Size */public unionfind (int size) {//initialization number this.size =        Size        Initializes the array, each of which points to its own id = new Int[size];        for (int i = 0; i < size; i++) {id[i] = i; }}/** * See which collection the element belongs to * * @param element to be viewed * @return The collection where element elements are located */private int Find (    int element) {return id[element]; }/** * Determine if two elements belong to a collection * * @param firstelement first element * @param secondelement Second element * @return <c     Ode>boolean</code> returns True if it is. */public boolean isconnected (int firstelement, int secondelement) {return find (firstelement) = = Find (secondele    ment); }/** * Merges the collection of two elements, that is, connecting two elements * * @param firstelement first element * @param secondelement the second element */pub LIC void unionelements (int firstelement, int secondelement) {//Find the collection where firstelement is located int firstunion = Find (Fir        Stelement);        Find the collection where secondelement is located int secondunion = find (secondelement);        If these two are not the same collection, then merge. if (firstunion! = secondunion) {//iterates through the array, merging the original firstunion, secondunion into secondunion for (int i = 0; I & Lt This.size;                i++) {if (id[i] = = firstunion) {Id[i] = secondunion; }}}}/** * This collection uses an array implementation, in order to see the internal data more visually, using the print array */private void Printarr () {for (i        NT Id:this.id) {System.out.print (id + "\ t");    } System.out.println ();        } public static void Main (string[] args) {int n = 10;        Unionfind Union = new Unionfind (n);        System.out.println ("initial:");        Union.printarr ();        System.out.println ("Connected 5 6");        Union.unionelements (5, 6);        Union.printarr (); SYSTEM.OUT.PRINTLN ("Connect1 2 ");        Union.unionelements (1, 2);        Union.printarr ();        System.out.println ("Connected 2 3");        Union.unionelements (2, 3);        Union.printarr ();        System.out.println ("Connected 1 4");        Union.unionelements (1, 4);        Union.printarr ();        System.out.println ("Connected 1 6");        Union.unionelements (1, 6);        Union.printarr ();        System.out.println ("1 5 is connected:" + union.isconnected (1, 5));    System.out.println ("1 8 is connected:" + union.isconnected (1, 8)); }}

And look up: tree-shaped structure

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and set Optimization: path compression

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and check Set (Java implementation)