This is an example of A star search, over a grid.
The robot in red, needs to get to the goal location in green.
Applying the transition function over the grid, the robot can find the reachable cells
from a given cell.
Starting from the start state, A star computationally expands the possibilities by constructing
a tree representing the different potential paths.
A star chooses the next option based on the length of the path up to the current cell
and the estimated distance to the goal, the heuristic.
In this way, it is efficient in selecting the promising options, eventually reaching
the goal.