Solve maze recursively using c++, cannot handle an exceptional case [closed] - c++

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I am using an algorithm that I found online to solve a maze.
FIND-PATH(x, y)
if (x,y outside maze) return false
if (x,y is goal) return true
if (x,y not open) return false
mark x,y as part of solution path
if (FIND-PATH(North of x,y) == true) return true
if (FIND-PATH(East of x,y) == true) return true
if (FIND-PATH(South of x,y) == true) return true
if (FIND-PATH(West of x,y) == true) return true
unmark x,y as part of solution path
return false
The algorithm works good on most mazes. But it cannot handle an exception:
######
#s. #
#.## #
#.####
#...f#
######
As shown in the picture, # is a wall, empty space is available path, s is the start and f is the finish.
And the '.' dotted line is the solution path marked after running the maze solving program.
In this case, the start point blocks the path into two way, and after running the program, there is one extra dot at the right side of the start point which cannot be unmarked.
I am wondering could anyone point out that why this happens to the above algorithm. And what extra check should I add to the solve() function? Thank you!

Answer 1

Probably the problem is occurring because you are revisiting already visited node.
Consider you are at the extra dot you are considering at beginning of function. Now on your west side you might have missed checking if it is a start point, and considering start point as not outside maze and available path. So now the program again starts checking from start and thus giving false positive result.
Without actual code its hard to debug though.
EDIT: It suffers from exact problem is was talking about above
Do you know where start point is. If so do following
Replace
if (ch =='.' || ch == '#')
return false;
with
if (ch =='.' || ch == '#' || ch=='s')
return false;