Methods and apparatus for grouping elements of element pairs into element sets are disclosed. A master processor transmits number pairs corresponding to the element pairs to worker processors, selectively assigns processing of one or more of the number pairs to the worker processors, receives developed sets of numbers from the worker processors, and processes the developed sets of numbers to generate the element sets. Worker processors process the assigned number pairs using a row hash table and a column hash table created from the number pairs corresponding to the element pairs to develop the sets of numbers.