Use linked list to represent set of objects.
Each object contains a pointer to the rep, the key, and a pointer to next.
Operations
Make-Set(x) ; O(1) rep(x) = x next(x) = NIL
Find-Set(x) ; O(1) return rep(x)
Union(x, y) ; (size of x) foreach object in rep(x) insert object into y rep(object) = rep(y) remove x