## rooms of a house

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### rooms of a house

I'm working on my first ever assignment dealing with Lisp. My function deals with 9 rooms of a house. 1.Library 2. Upstairs-bedroom 3. back-stairs 4. front-stairs 5. downstairs-bedroom 6. living-room 7.dining-room 8. kitchen 9.pantry
-The input is a room and the output is the number of direct rooms you can go from that room. The living room and Dining room's output is 3, the rest is 2.
-I tried 2 approaches to this, but not very successful. Could someone tell me what I'm doing wrong or the more efficient way of doing this?

Approach #1:
> (defun how-many-choices (loc)
(setq library 2)
(setq back-stairs 2)
(setq downstairs-bedroom 2)
(setq upstairs-bedroom 2)
(setq front-stairs 2)
(setq living-room 3)
(setq dining-room 3)
(setq kitchen 2)
(setq pantry 2))
HOW-MANY-CHOICES
> (how-many-choices 'back-stairs)
2
> (how-many-choices 'living-room)
2
>
--The living-room's output should be 3, not 2

Approach #2:
(defun how-many-choices (loc)
(if(eql loc 'living-room 'dining-room)
3
(= loc 2)))
HOW-MANY-CHOICES
> (how-many-choices 'library)
error: too many arguments
>
g0blu324

Posts: 6
Joined: Sat May 12, 2012 2:16 pm

### Re: rooms of a house

So in your first approach, the parameter loc isn't being used. Every time you call the function, it sets a number of (undeclared, assumed to be global) variables to integer values. The function always returns the value 2 because that is the return value of the expression (setq pantry 2) which is the last expression in the function.

Your second approach has a much better form, but eql is only specified for two parameters, and you are passing it three.

nuntius

Posts: 532
Joined: Sat Aug 09, 2008 10:44 am
Location: Newton, MA

### Re: rooms of a house

Ok thanks. Other than that function, I figured out 2 more functions from that out of 8 total. So now I have another question.

This time, I need to return either 2 or 3 rooms based on directional from each room, not just 1 number or string.
Example:
Input: Dining-Room
Output: ((east downstairs-bedroom) (west pantry) (north living-room)
Input: Library
Output: ((east upstairs-bedroom)(south back-stairs))

Should I be using append? condition statement (cond ((eql..... )) ? how many parameters should I send?

So here's what I've been trying:

#1 > (defun choices (loc)
(cond
(((eq loc 'library)'east 'upstairs-bedroom)'south 'back-stairs)
((((eq loc 'dining room) 'west 'downstairs-bedroom) 'east 'pantry) 'north
'living-room)))
CHOICES
> (choices 'library)
error: bad function - (EQ LOC (QUOTE LIBRARY))
> (choices 'dining-room)
error: bad function - (EQ LOC (QUOTE LIBRARY))

#2
> (defun choices (loc)
(if(eql loc 'library)
(append '(east upstairs-bedroom) '(back-stairs))
if(eql loc 'dining-room)
(append '(west downstairs-bedroom) '(east pantry) '(north living-room))))
CHOICES
> (choices 'library)
error: too many arguments
>

How is it too many arguements when I only took account 2 out of 9 rooms sofar

#3. I've tried doing a bunch of setq's and if statements but that's too many arguements.

Once I figure out how to do it for either 2 or 3 outputs, I can figure out the rest since there's always either 2 or 3 outputs.
g0blu324

Posts: 6
Joined: Sat May 12, 2012 2:16 pm