HPfGU contest -- solution to logic puzzle

[hpsmarty]

No: HPFGUIDX 47024

Here's the solution to the logic puzzle from the October contest.  
(The puzzle itself is at the bottom.)

If you have any comments, email them to me at hpsmarty at aol.com.  
Don't post them to the list!

Solution:

The first thing you have to do is figure out what all the items are 
in each category, and make yourself a solving chart.  There are five 
students – Harry, Hermione, Ron, Neville and Ginny – and they are 
each OWNERS of the transfigured homeworks as well as FINDERS of the 
butterflies (make sure your chart has separate sections for finders 
and owners).  The five subjects are Charms, Astronomy, History of 
Magic, Divination and Potions; and the five locations are by the 
fireplace, on the stairway,  under a table, on a photo and on a 
book.  The five colors of butterfly are a little harder.  Harry says 
that each butterfly has a different color and markings.  Red, green, 
yellow, and purple butterflies are mentioned, as is one butterfly 
that changes color.  It is also mentioned that the green butterfly is 
spotted, the yellow butterfly is solid, and there is one striped 
butterfly which Ginny catches, but we don't know yet which color it 
is (although it couldn't be green or yellow).

There are some clues in the text, before the numbered clues.  You're 
told that of the five students, one is a second year and the rest are 
third years.  Therefore, Ginny must be the second year, so she is not 
taking Divination.  The text also tells you that Hermione was working 
on Charms, and that Ginny caught her butterfly by the fireplace.

Harry's homework was not Divination (clue 4), Ginny was not taking 
Divination (text), Ron was working on Astronomy and Hermione on 
Charms, so Neville must have been working on Divination.  The text 
says that Ginny caught a striped butterfly, so she couldn't have 
caught the green butterfly (since it is spotted), the yellow 
butterfly (since it is solid), or the purple butterfly (since Neville 
caught that).  Ginny caught Hermione's homework (clue 5), which was 
Charms, so she couldn't have caught the changing color butterfly 
since that one was the Astronomy homework.  Therefore, Ginny caught 
the red butterfly, which was striped, and was transfigured into 
Hermione's Charms homework.

Hermione didn't catch Ginny's homework on the stairway (that was 
Ron's homework), or on the fireplace (Ginny caught that one), or on 
the book (Ron caught that one), or on the photo (Neville caught that 
one), so she must have caught it under the table.  Therefore, Harry 
didn't catch his butterfly under the table, on the photo, on the book 
or on the fireplace, so he must have caught Ron's homework on the 
stairway.  If Harry caught Ron's homework, then Ron must have caught 
Harry's homework, and Neville caught his own (clue 5).

The Charms homework was caught by the fireplace, the Astronomy 
homework by the stairway, and the Divination homework on the photo.  
The History of Magic homework was not caught under the table (clue 
2), so it must have been caught on the book and the Potions homework 
was the one caught under the table.

Harry's homework was not purple (that was Neville's Divination), or 
changing colors (that was Ron's Astronomy), or red (that was 
Hermione's Charms), or yellow (clue 4), so it must have been green.  
Therefore, Harry was working on History of Magic (clue 2), and Ginny 
must be the student who was doing her Potions homework, which must be 
the yellow butterfly.

Harry's History of Magic homework was a green spotted butterfly, 
caught by Ron on the book.
Hermione's Charms homework was a red striped butterfly, caught by 
Ginny by the fireplace.
Ron's Astronomy homework was a blinking, changing-color butterfly, 
caught by Harry on the stairway.
Neville's Divination homework was a purple butterfly, caught by 
Neville on the photo.
Ginny's Potions homework was a solid yellow butterfly, caught by 
Hermione under the table.

ORIGINAL PUZZLE:
Five Gryffindor students – four third-year students and one second-
year – are all doing their homework in Gryffindor Common Room when 
the Weasley twins rush in.  Fred yells "There's a troll in Hogwarts 
Castle, and it's headed towards Gryffindor Tower!"  "Quick, everyone 
get downstairs to the Great Hall," screams George. 

The five Gryffindor students rush through the painting of the Fat 
Lady, without noticing that Fred and George have not followed them.  
They run into to the Great Hall only to find a surprised-looking 
Professor McGonagall.  After they explain what happened, she says, "I 
would expect Gryffindors to be less gullible and more experienced.  
Obviously, Fred and George Weasley wanted you all out of the way so 
they could perform some sort of mischief.  I suggest you return to 
the Gryffindor Common Room immediately before you find that your 
socks have been charmed to play snare drums all night long."

The five embarrassed Gryffindors hurry back up the stairs and through 
the secret corridors.  When they get back to Gryffindor Tower, they 
find that the Common Room is full of colorful, flying, swooping 
butterflies – and that the parchments containing their homework are 
missing.

"Oh no," groans Ron, "Fred and George transfigured all of our 
homework into butterflies!"

"How will I ever finish my Charms assignment?" moans Hermione.

"It looks like a simple charm," says Harry, carefully watching the 
butterflies soar around the room.  "They each seem to have different 
colors and markings, and they land for a few seconds every five 
minutes or so.  We just have to catch them."

"That's easy for you to say, Harry, you're a seeker – you can grab 
small flying things. I won't be able to catch anything!" Neville says 
dejectedly.

"You can do it, Neville," says Ginny encouragingly, "It's not 
hard."  "You just have to watch them carefully and wait until they 
land," she adds, and then leaps up and grabs a striped butterfly 
resting by the fireplace.

And each of the students, including even Neville, do manage to catch 
a butterfly.  Eventually, Hermione finds a spell to transfigure the 
butterflies back into homework parchments, and it turns out that only 
one student has caught his own homework.

Using the clues in the text above and listed below, along with what 
you know about Hogwarts and its students, can you figure out which 
student caught which color butterfly, where he or she caught it, and, 
when transfigured, who each homework belonged to and what subject it 
was?  (Each student was working on a different subject.)

1. The most spectacular butterfly had colors which changed every time 
it flapped its wings, blinking from red to yellow to green as it 
swooped around the Common Room, until it was finally caught on the 
stairway and transfigured back into Ron's Astronomy homework.

2. It was the green spotted butterfly, not the butterfly caught under 
a table, that was the History of Magic homework.

3. Neville was helped in his efforts to catch a large purple 
butterfly by the members of the 1845 Gryffindor House Quidditch Team, 
who yelled advice when the butterfly landed on their photograph.

4. The large, solid yellow butterfly turned out to be neither Harry's 
homework nor the Divination homework.

5. The two boys who did not catch their own homework parchments 
caught each other's, as did the two girls.

6. One of the butterflies landed on a copy of *The Monster Book of 
Monsters,* which helped Ron catch it.

7. One student was working on Potions homework, and one butterfly was 
red.