Thanks for the nice competition. However based on my memory on the previous year competition, I believe this competition could have been more challenging. I hope to see a puzzleup-2009 with more higher information between intelligence and score table(as was 2005)

   Thanks and archive question

To the Puzzleup Team: Thank you so much for all your efforts in giving us a challenging and fun competition!

I am interested in accessing some of the puzzles from previous years. Is there any way they could be made part of the Archive?

Again, many thanks to all, and Happy New Year!

Clive Dawson
Austin, Texas, USA

   Scoreboard

Ring...ring...ring...ading!
Last call for November Scoreboard!

   [Geometric Sequence] easy but nice one

It just took couple of minutes.

   [Height Row]

a little crazy

   [Height Row]

An interesting side question: Find the closed form expression for general n.

   Clarification for Question #14

A few fellow PuzzleUp contenders e-mailed us and commented on the question text. It was apparent that the shape of a 4x4 room was misunderstood. To clarify the question, a short expression “(square array)” was added after the expression “4x4”. Also, the image above the question text was altered to give a visualisation of a 4x4 square array arrangement.

The question text now reads:
You will place 16 people with different heights to a meeting room with a 4x4 (square array) arrangement of seats such that each person will be taller than both the person in front of and left to her/him.
In how many different ways can this operation be carried out?
If the question was for 9 people and a 3x3 arrangement of seats, then the answer would be 42.


Previously the question text was:
You will place 16 people with different heights to a meeting room with a 4x4 arrangement of seats such that each person will be taller than both the person in front of and left to her/him.
In how many different ways can this operation be carried out?
If the question was for 9 people and a 3x3 arrangement of seats, then the answer would be 42.

We wish a good competition for all our contenders.

   Score Table

Thanks for the update - just in short times.

   [Spherical Triangles]

Great! Now waiting for hyperbolic triangles;-)

   [Spherical Triangles] physical representation

just like the intersecting planes problem in a previous year, this problem had me scrapping pencil and paper in favor of building a model. hooray for balled up notebook paper and rubber bands!

   [Fourteen]

One of the best problems I have ever seen. It will give you a lot of satisfaction if you do it without the computer. I loved solving it without the help of a computer.

   [Tangential Circles]

Glad you changed the wording. Your site was unreachable for a couple of days earlier this week

   [11 Footballers]

It would be nicer if the question was asked for 30 footballers. It would be more fun and would resemble the "100 numbers" problem asked in 2006. Although I detested the 100 numbers problem at that time for being too tough, I now believe that such problem should be asked to get the competition more exciting.

   [Tangential Circles] Change in Question #11 "Tangential Circles"

Dear Puzzleup Contenders,

The question #11 “Tangential Circles” has been changed.

The previous text of the question was:
We have four circles with different radii. In how many different ways can these circles be placed, under the condition that each of them will be tangential to all the other circles.

The layouts which are not topologically distinct will be counted once. For example, for three circles, having radii A>B>C; the layout where A and B are inner tangential and C is outer tangential; and the layout where A and C are inner tangential and B is outer tangential are topologially identical.

If the question was asked for two circles, the answer would be 2 (as shown in the picture above); and if it was asked for three circles; then the answer would be 4.


The question text now reads:
You will draw four circles on a plane such that each of them will be tangential to all the other circles. How many different drawings can you form?

A drawing formed by changing the relative sizes of the circles in a given drawing does not count as a different drawing.

If the question was asked for two circles, the answer would be 2 (as shown in the picture above); and if it was asked for three circles; then the answer would be 4.

Please enter your answers accordingly. Our apologies for the inconvenience.

   [Tangential Circles]

Nice Problem. Quite easy, but i liked it a lot more than those only-by-computer-solvable problems.

   [Five Boxers]

Nice puzzle image! :-)

   [A Target Board] nice one

nice one

   Leaderboard

When can we expect to see a leaderboard? We are almost half-way through the contest now...

   [A Target Board] Change in Question #8

Dear Puzzleup Contenders,

The question #8 “A Target Board” has been changed.

The previous text of the question was:
A target board consists of three parts, and each part has a positive
integer on it. Each contender will make 9 shots, and will have a total
point according to the numbers on the hit parts. The probabilities of
hitting each of these parts and missing the board are equal. In order to
maximize the probability of getting a total of 44 points, what should the
numbers on these parts be?
Enter the numbers in an ascending order, without leaving any spaces
between them.

The question text now reads:
A target board consists of three parts, and each part has a different
positive integer on it. Each contender will make 9 shots, and will have a
total point according to the numbers on the hit parts. The probabilities
of hitting each of these parts and missing the board are equal. In order
to maximize the probability of getting a total of 44 points, what should
the numbers on these parts be?
Enter the numbers in an ascending order, without leaving any spaces
between them.
Example: If the numbers on the parts were 1, 2 and 3; then your answer
should read 123.

Please enter your answers accordingly. Our apologies for the inconvenience.

   

@angsay: Yes you are right but, to my understanding, there is no trick involved & you just need to count in a certain pattern so it is better and more reliable to write a code rather than counting manually.

@laydogan: Q7 means the current puzzle (Fourteen), thought you got mislead by the popularity level.

   [Fourteen]

Thank you, usinghal, to agree with me but you said that you solved the Q7 (Lottery) within 1 or 2 minutes without computer help, really?

   [Fourteen]

Utkarsh, I think none of the problems except "lottery ticket" needs a computer.

   [Fourteen]

Thanks a lot for re-phrasing this problem!

   Change in the Question

The text of the question #7 "Fourteen" has been changed in order to make the meaning more clear.

We wish a good competition for all our contenders.

PuzzleUp Team

   

There are only 2 categories of problems posted here:
(a) can not be solved without a computer and requires a real brain storming to write a working code
(b) can be solved without a computer and take only a minute or two to solve like puzzle 3,6,7
I completely agree with laydogan but out of the choices available, I will prefer (b).

   [Fourteen]

I do agree with Wong.
I also expect problems which are more
challenging,still not asking for a computer assistance.

   [Fourteen]

Though it can be solved without computer, but it is a little easy one.

   [Fourteen] no computer here!

I like this problem because one cannot solve it with the computer since the number is too large.

   [Fourteen] My preference

I prefer the ones that can be solved without a computer help (not for this one, 14) and take at least a few hours to solve.

   [Fourteen] i liked that

my vote for the best problem of the season goes to this one :)

   [Fourteen]

Nice problem.

   [Five Questions]

Easiest one...

   [Five Questions]

The best problem this season. Hope to see more of those.

   [Four Regions]

Is it better to number the squares as 1 to 16 rather than just taking black and white chess board to make two different ways distinct which appears identical in the present scenerio.

   [A Lottery Ticket]

@Utkarsh:Unfortunately,I cannot think of a logical way.This problem is mathematical,but does not challenge a programmer.I think it is not in the interest of the competition.