Summary: A non-slicing approach, Corner Block List (CBL), has been presented recently. Since CBL only can represent floorplans without empty rooms, the algorithm based on CBL cannot get the optimum placement. An extended corner block list, \(\text{ECBL}_\lambda\), is proposed. It can represent non-slicing floorplan including empty rooms. Based on the optimum solution theorem of BSG (Bounded-Sliceline Grid), it is proved that the solution space of \(\text{ECBL}_n\), where \(n\) is the number of blocks, contains the optimum block placement with the minimum area. A placement algorithm based on \(\text{ECBL}_\lambda\), whose solution space can be controlled by setting \(\lambda\), the extending ratio, is completed. When \(\lambda\) is set as \(n\), the algorithm based on \(\text{ECBL}_n\) is the optimum placement search algorithm. Experiments show that \(\lambda\) has a reasonable constant range for building block layout problem, so the algorithm can translate an \(\text{ECBL}_\lambda\) representation to its corresponding placement in \(O(n)\) time. Experimental results on MCNC benchmarks show promising performance with 7% improvement in wire length and 2% decrease in dead space over algorithms based on CBL. Meanwhile, compared with other algorithms, the proposed algorithm can get better results with less runtime.