1. A data processing unit, comprising: a solution search processor to perform solution search processing of a plurality of physical objects in which the plurality of physical objects are transferred from a transfer origin to a transferring destination via a predetermined location and in which each object has a loading state signified by a data representation comprising a heap number variable of the object loaded in a predetermined physical location and a coordinate value indicating a loading order of the object in the heap, and an initial condition inputter to input as an initial condition a heap number variable, a transfer order variable, and an identification data for each of the plurality of physical objects, wherein the heap number variable is either the number of the heaps formable in the predetermined location or an identification data for each of the heaps formable in the predetermined location, and the transfer order variable is a coordinate value indicating a loading order of each of the physical objects in the heaps; and a constraint condition deriver that derives first constraint conditions on transferring order of the plurality of physical objects from the transfer origin to the predetermined location based on the initial condition, and first constraint conditions on transferring order of the plurality of physical objects from the predetermined location to the transferring destination based on the initial condition, wherein said solution search processor performs the solution search processing based on the initial condition inputted by said initial condition inputter by: determining partial solution candidates by allocating values to the heap number variables based on identification data for each of the plurality of physical objects and the number of heaps at the predetermined location, the constraint condition deriver deriving second constraint conditions on a transferring order of each of the objects from the transfer origin to the predetermined location and second constraint conditions on a transferring order of each of the objects from the predetermined location to the transferring destination, based on the partial solution candidate generated by said solution search processor, a constraint investigator judging whether a partial solution candidate generated by said solution search processor satisfies the first and second constraint conditions, an outputter, outputting a partial solution when the partial solution candidate satisfies the first and second constraint conditions, and said solution search processor continuing the solution search when the partial solution candidate does not satisfy the first and second constraint conditions.