In developing a recursive solution, consider the base cases first. What situation(s) cause the algorithm to stop?

1. We have arrived at a location which is off the data structure. It is important to catch this situation first to avoid an array indexing error.
2. Encountering a '*' character means that we have run into a wall. The algorithm should stop.
3. Arriving at a location which has a row or column value equal to 1 or MAXROW or MAXCOL. We have found an exit point.

The general case of encountering a blank space requires the following steps:

1. Change the character value from the blank space to the '!' character.
2. Check to see if we are at an exit point. If we are, print the maze with a trail of '!' markers to the exit point.
3. If we are not at an exit point, make 4 recursive calls to check all 4 directions, feeding the new coordinates of the 4 neighboring cells.

When an exit point is found, we want to print only the successful trail of '!' marks that leads to an exit. As a result, it is necessary for each recursive call to work with a copy of the array. Why is this? If a reference to the original array is passed with each recursive call, the placement of '!' marks would be permanent in the data structure.