A method of fabricating an integrated circuit (IC) with first and second different lithography techniques includes providing a layout of the IC having IC patterns; and deriving a graph from the layout. The graph has vertices and edges connecting some of the vertices. The vertices represent the IC patterns. The edges are classified into at least two types, a first type connecting two vertices that are to be patterned separately with the first and second lithography techniques, a second type connecting two vertices that are to be patterned in a same process using the first lithography technique or to be patterned separately with the first and second lithography techniques. The method further includes decomposing the vertices into first and second subsets, wherein the IC patterns corresponding to the first and second subsets are to be patterned on a wafer using the first and second lithography techniques respectively.