A 63 - year - old female presented with sudden headache, vomiting and weakness of the left limb, and became unconscious 10 minutes later. Examination revealed elevated blood pressure, no response to pain stimulation on the right limb and positive right Babinski sign. Brain CT showed a high - density shadow about 5 cm in diameter in the right basal ganglia. After admission, the right pupil had no response to light, while the left pupil had a response to light. What is the most likely diagnosis?