If i smoke after someone who has genital warts can i get it ?

No: HPV, the virus that causes genital warts, is found in semen and vaginal secretions, and is not transmitted by saliva. It is possible, although rare, for HPV to be spread through oral sex (cunnilingus or fellatio). The virus does not survive generally in oral fluids and the chances of transmission through smoking the same cigarette as someone with HPV would be highly unlikely.

No: The HPV which causes genital warts must come in contact with the genital area to transmit the warts and I can't imagine how a cigarette would come in contact with both your genitals and the genitals of someone else. However, if you do contact the virus, smoking decreases your immune systems ability to control it and you are more likely to develop warts and it is harder to get rid of them.