[TheRealDevonMcC]

A programmer, an engineer, and a physicist are in adjacent hotel rooms. Each has a pitcher of water beside the bed. A fire starts in the wastepaper basket in each room.

The physicist wakes up, sees the fire, estimates exactly how much water is needed to put it out, and pours exactly that amount from the pitcher, dousing the flames.

The engineer wakes up, sees the fire, pours the entire pitcher of water on it, then refills the pitcher and douses it again to be safe.

The programmer wakes up, sees the fire, sees the pitcher of water, decides it's a solvable problem, and goes back to sleep.

[StavrosK]

I know it with "The mathematician's bin was full, so he lit it on fire, reducing the problem to one with a known solution".

[beervirus]

Makes more sense with a mathematician than a programmer.

[saagarjha]

The programmer looks online for documentation on how to use the water, finds it too complicated, dumps the water out the window, then dumps the contents of the wastebasket out after it. Seeing the fire gone the programmer later goes on to give a conference talk about the importance of a good throwing arm in fire safety.

[el_benhameen]

I chuckled at the original, but yours really got me. I feel seen.

[vharuck]

Variant I heard, had a physicist, engineer, and mathematician sharing a room.

The first two wastepaper basket fires were taken care of the same ways by the physicist and engineer.

Then a third fire appears, but on the curtains. The mathematician says he'll take care of it, so the others go back to sleep. The mathematician removes the curtains, puts them in the wastepaper basket, and says, "Now it's a solved problem." He then goes back to sleep.