1. A computer-implemented method of determining a first optimal solution to a first layout problem requiring an optimal layout of a multiplicity of elements in a predetermined region under a first set of conditions, which includes a uniformalization condition such that the multiple elements are distributed in substantially uniform density throughout the predetermined region, as the first optimal solution, wherein said first layout problem is analyzable into the uniformalization condition and a second layout problem requiring an optimal layout of the multiple elements in the same predetermined region under a second set of conditions, which consists of the remaining conditions of the first set of conditions other than the uniformalization condition, as a second optimal solution, comprising the steps of: (A) generating a linear combination of a first objective function, which represents the second set of conditions of said second layout problem, and a second objective function, which represents the uniformalization condition of said first layout problem, as a third objective function, which is assumed to represent the first set of conditions of said first layout problem; and (B) optimizing said third objective function generated in said step (A), whereby the first optimal solution to the first layout problem is determined.