1. A combinatorial computing apparatus in a parallel computing system, comprising: an input-setting unit configured to receive a first setting relating to multiple groups of input data and a second setting relating to the combinatorial mode among the multiple groups of input data; a data-obtaining unit configured to obtain a data combination of the multiple groups of input data according to the first setting and the second setting; and at least one combinatorial operating unit configured to perform a desired calculating operation on the data combination.