how can a write a code for simulation

Like a square meter - need to scale it - not sure
When the room is clean, it's done

edit
we know the area of the robot - maybe we can multiply that by distance traveled

like this

The area is dependent on the size of the robot. I am not sure but I think that a simple calculation of area would be the width of the robot times the distance. That however might be too simple if you need to exclude area that has already been swept. The distance would depend on the timer and the distance moved for each interval. You control the distance moved for each interval.

You are still being vague so I am still being vague.

actually i know c sharp but this is my first simulation that i did something but just a disk move,
i want to add how much area sweep and distance?

Are you writing a Windows application; in other words, it is just a simulation, correct?

What part do you need help with? You will need to move the robot at a certain speed, which will require a timer. You will need to draw the robot; what else do you need to draw that you are asking for help with? Do you need help with calculating a 120 degree angle? You need to be specific about things like that.