public class UnionFind {
public static class Pointer {
Pointer pointerForJoin;
}
// number of elements in array
private static final int N = 10;
private static Pointer[] connection = new Pointer[N];
private static void union(int a, int b) {
if(connection[a] != null && connection[b] != null) {
if(connection[a].pointerForJoin != connection[b].pointerForJoin )
connection[b] = connection[a].pointerForJoin = connection[b].pointerForJoin = connection[a];
} else if(connection[a] != null) {
connection[b] = connection[a];
} else if(connection[b] != null) {
connection[a] = connection[b];
} else {
connection[a] = connection[b] = new Pointer();
connection[a].pointerForJoin = connection[b].pointerForJoin = connection[a];
}
}
private static boolean isConnected(int a, int b) {
if (a == b) return true;
if(connection[a] == null || connection[b] == null) return false;
return connection[a].pointerForJoin == connection[b].pointerForJoin;
}
public static void main(String[] args) {
union(1,2);
union(2,3);
union(5,6);
union(8,9);
union(8,2);
System.out.println(isConnected(8,3)); //true
System.out.println(isConnected(8,2)); //true
System.out.println(isConnected(9,1)); //true
System.out.println(isConnected(1,6)); //false
System.out.println(isConnected(1,7)); //false
System.out.println(isConnected(0,0)); //true
}
}
```
