Police are investigating three separate slashings in Brooklyn that left three men hospitalized over the weekend. The first attack happened at about 6:20 a.m. Saturday on a northbound Q train, as it approached the Cortelyou Road station. Police said a 37-year-old man was slashed in the face by an unidentified man armed with a sharp object. The attacker got off the train at the station and ran south on Cortelyou Road. Police released a photo of the suspect, described as a man with a dark complexion and medium build, about 6 feet 2 inches tall. He was last seen wearing a black jacket, beige hooded sweatshirt, black shorts, white sneakers, a black face mask and carrying a black and gray bag. Hours later, around 10 p.m. Saturday, officers responded to Brooklyn Avenue and Foster Avenue for a 53-year-old man also slashed in the face. A man wearing all black clothing and a mask fled the scene, according to police. A third slashing was reported around the corner from the previous one,…..