Implement Union-Find

Implement a Union-Find (disjoint set union) over the elements 0 to n - 1. Initially every element is in its own set.

Implement the UnionFind class:

• UnionFind(n) creates n singleton sets.
• union(x, y) merges the sets containing x and y. Returns true if they were in different sets (a merge happened), false if they were already together.
• connected(x, y) returns true if x and y are in the same set.
• componentSize(x) returns the number of elements in the set containing x.
• count() returns the current number of sets.

Use path compression and union by rank (or size) so that operations are near-constant time. The representative chosen for a set is not observable through this interface.