There are $n$ holes in line at a distance $1 cm$. We have forks with $2$ tines at the same distance.
a) how many ways to plug $k$ such forks?
b) what changes if the holes are in the circle?
There are $n$ holes in line at a distance $1 cm$. We have forks with $2$ tines at the same distance.
a) how many ways to plug $k$ such forks?
b) what changes if the holes are in the circle?