A modified O-Tree based packing algorithm and its applications

In this paper, we propose a new packing algorithm based on O-Tree representation that can reduce the time cost of turning an O-Tree into an admissible O-Tree and decoding it into a placement. By introducing a vertical contour into our algorithm, we replace the OT2OCG (O-Tree To its Orthogonal Constraint Graph) and CG2OT (Constrained Graph To O-Tree) procedures by a single OT2PL one with 50% timesaving in practical cases. Our algorithm can be applied to various problems such as placement with boundary constraint and with rectilinear blocks. A genetic algorithm is used to solve both problems and we additionally insert a block as an internal node of O-Tree without increasing the time complexity when perturbing the O-Tree. The effectiveness of our algorithm is justified by experimental results.