Turn two switches ON, and left one switch OFF. Wait 10 minutes. Then shut one of the ON switches OFF. One switch is ON and two are now OFF. Immediately go into the room. If the light is on, you know it's the switch that is still ON. If the light is off, feel the light bulb. If the bulb is cold, it's the light switch that you never turned ON. If the bulb is still warm but the light is off, it's the switch you turned ON but then turned OFF prior to entering the room.
This can’t be the answer as the initial situation stated you can’t touch the switches a second time.
I liked the answer provided above, checking the lights' bulbs, but in case that you can't touch the switches after 10 min, then I will propose the following: turn 2 switches on. Go to the room. You have one switch off and one light off. So these two are a pair. From the two switches on and the two lights on, ask somebody else to turn off one switch. Then you can establish the connection between one switch and one of the on lights. The third match would be the remaining switch and light. I would say that the instructions never said that you can ask for somebody elses help. What is not prohibited is allowed.
