10478 - The Falling Pillars

[shadowlightning]

10478 does anybody have any idea what the correct output for 10478 is. I have a complete application that I am sure calculates the angles correctly but the judge keeps telling me that it is not correct. How do I know what it is that is not correct?

[Dominik Michniewski]

Not only you think, that there is something strange with this problem. I have program, which should work with it, but I got WA too.
Maybe problemsetter has some super special test cases for us ))
Would problemsetter give us some hints, please ?

DM

[shahriar_manzoor]

The problem is fixed, but still hard to get accepted.

Hint: Read the boldfaced text properly.

[shadowlightning]

after the rejudge my submissions have now been accepted. - thank you

[Dominik Michniewski]

I think that I have problem with handle special cases.
Shadowlightning - could you tell me: is there any special cases for "Impossible." except d <= w and h <= d-w ??

Best regards
DM

[Cletus]

Code: Select all

Can somebody say what the question really means please?
There are parts of the problem statement that are at least
slightly wrong, and it does not fully define essential terms.

1. The output format says "rounded up-to three digits after the 
decimal point". I presume it doesn't really mean rounded UP;
that would be a very odd requirement, and would also make
the sample output wrong. Can someone confirm that it should
really just say "rounded to..."?

2. What is meant by "impossible"? Is it physically impossible
situations such as w>d or h<0 that the problem statement
forbids anyway, or does it mean situations in which it is
impossible for the pillar to fall, such as w=d, or does it mean
situations like h<d (adjusted) in which the pillars can fall, but 
would lie on the ground and not touch, when the question clearly 
states that they will touch "1 touches 2 at P..."?

3. What are the boundary conditions? If the centre of gravity
is directly above the balancing point, is that considered stable
or unstable?

There are so many things that can only be guessed at, and when
the problem setter actually says rather mysteriously that it is
still hard to get accepted, one might not feel very enthusiastic
about spending time on this question.

[shahriar_manzoor]

Read the following lines carefully

A situation is unstable only when a fallen pillar cannot maintain that fallen position on it's own. A fallen pillar means, the status of a pillar when it falls towards right as much as it is allowed to by the given configuration.

[Cletus]

These frequently quoted words do not answer
the question:

"A situation is unstable only when a fallen pillar
cannot maintain that fallen position on it's own.
A fallen pillar means, the status of a pillar when
it falls towards right as much as it is allowed to
by the given configuration"

Firstly, NO pillar can maintain its fallen position
on its own. It always relies on the pillar to the
right, on which it has fallen. Taking those words strictly
means that only pillars lying flat on the ground
are stable, and the sample output shows that isn't
what is meant.

But that is completely missing the point anyway. It
says nothing about the boundary condition. Forgetting for
the moment about all pillars to the left, if a pillar rests
so that its centre of gravity is to the right of its own
base, it is stable, and to the left it is unstable. What about
the case of exactly above, neither right or left.

And what about points 1 and 2: the menaing of impossible,
and whether rounding UP was really intended?

[shahriar_manzoor]

But that is completely missing the point anyway. It
says nothing about the boundary condition. Forgetting for
the moment about all pillars to the left, if a pillar rests
so that its centre of gravity is to the right of its own
base, it is stable, and to the left it is unstable. What about
the case of exactly above, neither right or left.

There is no such case in the input and also inputs are such that no floating point error occurs.

The definition of fallen status says that a pillar can fall on the pillar to its right. So maintaining fallen status on its own means without the help of the pillars to its left.

[Cletus]

OK, that is nice to know.
But you see what I mean now, don't you? The "on its own"
phrase wasn't as exact as it was intended to be.

Now, can somebody please say what "impossible"
really means?

And a confirmation that "rounded up" really just
means "rounded" would be nice too.

[shahriar_manzoor]

"rounded upto" and "rounded up" is not same. rounded up may mean like ceiling() but "rounded upto" means rounded to, and I have a feeling that your trouble is not with "Impossible" but with "Unstable"

[Cletus]

No, my problem is with what you mean by "Impossible",
I am not asking about "unstable".

My problem is NOT being surprised by WA's. It is not
knowing what the question is intended to mean.

As I said before, "Impossible" could mean:

(A) Physically impossible: such as w>d or h<0 or h=0, or

(B) Impossible according to the problem statement, which
covers most of the same possibilities as (A), or

(C) Situations in which it is impossible for the pillar to fall,
such as w=d, or

(D) Situations in which the pillars can fall, but would not make
contact, and would end up flat on the floor, which would
normally be considered perfectly OK, but the problem
statement says the pillars must touch: "1 touches 2 at P...",
or

(E) Something else that I haven't thought of, or

(F) Some cobination of the above.

[shahriar_manzoor]

I think if someone else who has got accepted for this problem replies. Then I will be able to find where the problem statement is not clear.

[nikhil]

The Falling Pillars
10478
can any body help me to solve???????
thanks

[Jewel of SUST]

Yes I got accepted for this problem.
And I thought the problem statement could be
a bit more clear. Special case of this problem is as complex
as the main logic become minor. And I don’t know
why Shahriar Manzoor like to do that whenever he can.
This problem reminds me another problem #10323,
Factorial! You must be kidding!!!