Re: Knife, 3-foot lead pipe, or pistol with 1 bullet?
If you had the gun, pretty easy to get another weapon if one charges at you, but difficult if both do it at the same time. Shoot too early and you can miss, leaving you with a gun that can only serve as a crappy shield or a blunt weapon. Best to wait for a person to come at you, but it'll be a 1v1 afterwards.
If you have the knife or the pipe, going after the gun guy would most likely end up in you getting shot. Aside from that, the dude with the other melee weapon would turn on you when you make impact with the gun guy. If you go after the other melee weapon carrier, you'd be easy pickings for the gun guy as you'd be likely tired or too distracted to dodge the bullet. You can't guarantee the gun guy won't just try to shoot one of you immediately.
Or you can guarantee a least painful death by choosing the gun and opting to shoot yourself.
Best option would be the gun, hope that the guy with the pipe goes for you and kill him to take his pipe. The pipe has more range than the knife and is much easier to take because the handle is on both ends unlike the knife. It won't be pretty or success won't be guaranteed, but plan wise, this has the least amount of openings.