Fast and reliable inverse design has long been a sought-after goal in the field of nanophotonics, particularly in light of the rapid advancements in computational science and numerical tools. In this work, we present a novel approach for topology optimization involving a GPU-accelerated Discrete Dipole Approximation (DDA) algorithm, seamlessly integrated with other cutting-edge techniques to enhance its accuracy, speed, and robustness. Utilizing this sophisticated computational framework, we have designed a range of highly efficient nanostructures and conducted an in-depth exploration of the underlying physics. The first and second parts provide a comprehensive description of the algorithm's implementation and performance. The third section showcases several nanostructures designed using the proposed algorithm, elucidating the associated physics and demonstrating the effectiveness of our approach in addressing contemporary challenges in nanophotonic device engineering.