Example:

If we have three robots $1,2,$ and $3$ and the $($unknown$)$ order along the line from left to right is $2,3,1,$ your algorithm should return either $2,3,1($the left to right order$)$ or $1,3,2($the right to left order$).$ Returning any order other than these two is incorrect. In this example adjacent$(1,2)$ would return false, since robot $1$ and robot $2$ aren$$t adjacent on the line. adjacent$(1,3)$ would return true, since robot $1$ and robot $3$ are adjacent.

Remember to:

a$)$ describe your algorithm in plain English, b$)$ argue its correctness, and

c$)$ analyze its time complexity.