QuickFindUF.java

package com.example.unionfind;

/**
 * Created by gnusosa on 2/5/15.
 */
public class QuickFindUF {

    private int[] id;

    public QuickFindUF(int N)
    {
        id = new int[N];
        for (int i = 0; i < N; i++)
            id[i] = i;
    }
    public boolean connected(int p, int q)
    { return id[p] == id[q]; }

    public void union(int p, int q)
    {
        int pid = id[p];
        int qid = id[q];
        for (int i = 0; i < id.length; i++)
            if (id[i] == pid) id[i] = qid;
    }
}

UnionFindRun.java

package com.example.unionfind;

/**
 * Created by gnusosa on 2/5/15.
 */
import com.example.unionfind.QuickFindUF;
public class UnionFindRun {
    public static void main(String[] args) {
        QuickFindUF uf = new QuickFindUF(10);
        uf.union(1,9);
        uf.union(6,0);
        uf.union(4,5);
        uf.union(2,9);
        uf.union(9,7);
        uf.union(3,6);
    }
}