The Nineteenth Byte

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06:00

-1

Q: c++ , if else statement doesn't work , where is my mistalke? thanks for the help!

by the following code it should be printed how many times is every element appears in an array but it seems that i have a mistake in my code, that i couldn't recognize the numbers 0.3 and 0.6 are counted as 0.0 i would be grateful if i get some help. void getTotalA(int n, float a[], int b[]);...

c++

Anonymous

@LeakyNun Maybe, but then the stack would have to be conserved across every iteration. It's less complicated to just give it a new stack.

Anonymous

@LeakyNun That's not a bug. That's a feature that's only present in the newest version. TIO is a version or two behind.

Anonymous

Speaking of which... @Dennis, pull Actually please?

Leaky Nun

@Mego Cool, then I can use 'bu to produce c

Anonymous

Yep

Leaky Nun

06:09

Also, what is the "extended command"?

Anonymous

@LeakyNun 11 bytes: 93+#"{:x}"f

Anonymous

@LeakyNun Nothing yet

Leaky Nun

@Mego wow, nice

I'm still going to use 'bu though

Destructible Watermelon

yo

Anonymous

@LeakyNun If you're talking about the challenge I think you're talking about, that feature post-dates it

Leaky Nun

06:12

@Mego ... y u no say earlier

I've changed everything already

Anonymous

Because it's your responsibility to make sure that the language features you use are older than the challenge?

Leaky Nun

sure

Why doesn't this work?

Anonymous

Because you need % for old-style formatting

Leaky Nun

Nice thanks

Anonymous

After you post your competitive solution, I'm going to try to come up with a non-competitive optimal set of solutions using the entire code page.

Leaky Nun

06:26

Ok

Heck, with your newly added feature, everything can be done in under 3 bytes

Sherlock9

Which challenge, Leaky?

Leaky Nun

25

Q: Print every printable ASCII character without using it

In a programming language of your choice, write 95 programs, each of which outputs a different one of the 95 printable ASCII characters without that character occurring anywhere in the program. For example, if your language was Python, your program that outputs the character P might be print(ch...

code-golf string restricted-source printable-ascii

Sherlock9

Ah, nice

Sp3000

Is ' doable in 3?

Leaky Nun

why would it be?

Sp3000

06:30

You said "everything can be done in under 3 bytes"?

Leaky Nun

Oh, with the newly added feature

Anonymous

Nope

Anonymous

Can't use ' to make '

Leaky Nun

@Mego Except the space

Anonymous

"&"u for 4

Leaky Nun

06:31

The space would need to be :32c

since you added u but not D

Anonymous

Yeah D is coming next

Anonymous

I ran out of time to add the functionality to D

Anonymous

There, D now works similarly

Leaky Nun

06:44

0

A: Print every printable ASCII character without using it

Actually, 383 For easy reference, the first column is the character code, the second column is the character, and the third column is the code. The code for 0 is a single space. 032 :32c 033 ! HN 034 " 9Fc 035 # :35c 036 $ :36c 037 % :37c 038 & :38c 039 ' :39c 040 ( :40c 041 ) :41c 042 * :42...

@Mego

114 r 9R$F

@Mego \o/

Anonymous

Nice

orlp

07:06

anyone here?

I don't understand this problem

golf.shinh.org/p.rb?f+0

Leaky Nun

@orlp you are given the values of f(1) ... f(10)

your task is to find f(0)

orlp

@LeakyNun but f(0) is always 0...

f(x) = Σ[n=0..9]{a_n*x^n}

see my problem?

Leaky Nun

@orlp 0^0 is 1 here

ASCII-only

@orlp How?

orlp

@ASCII-only apart from because powers of 0...

but 0^0 is undefined

normally

ASCII-only

07:16

@orlp No, it's 1 normally

Leaky Nun

@orlp just assume that it is 1 here

orlp

so if I understand this correctly

we have this matrix

[1  1   1    1     1      1       1        1         1          1 | i_1]
[1  2   4    8    16     32      64      128       256        512 | i_2]
[1  3   9   27    81    243     729     2187      6561      19683 | i_3]
[1  4  16   64   256   1024    4096    16384     65536     262144 | i_4]
[1  5  25  125   625   3125   15625    78125    390625    1953125 | i_5]
[1  6  36  216  1296   7776   46656   279936   1679616   10077696 | i_6]
[1  7  49  343  2401  16807  117649   823543   5764801   40353607 | i_7]

Leaky Nun

yes

orlp

err i should've been a

oh no

a is the variables in the columns

Leaky Nun

multiplier

orlp

07:23

[1  1   1    1     1      1       1        1         1          1][a_1]    [ f(1)]
[1  2   4    8    16     32      64      128       256        512][a_2]    [ f(2)]
[1  3   9   27    81    243     729     2187      6561      19683][a_3]    [ f(3)]
[1  4  16   64   256   1024    4096    16384     65536     262144][a_4]    [ f(4)]
[1  5  25  125   625   3125   15625    78125    390625    1953125][a_5]    [ f(5)]
[1  6  36  216  1296   7776   46656   279936   1679616   10077696][a_6]  = [ f(6)]
[1  7  49  343  2401  16807  117649   823543   5764801   40353607][a_7]    [ f(7)]

Leaky Nun

yes

orlp

well

just one equals sign

Anonymous

Unless you're multiplying row vectors by single-element vectors

Anonymous

In which case the multiple equals signs makes sense :P

Destructible Watermelon

I had a good idea for a challenge

I'm going to sandbox it soon

sandbox'd

orlp

07:31

@LeakyNun I don't see an elegant solution

Leaky Nun

@orlp me neither

orlp

do you know if it's possible to solve a matrix using sympy

but without concrete values

Destructible Watermelon

0

A: Sandbox for Proposed Challenges

Play the centipede game king-of-the-hill (please note that I need to learn how to make a controller) In this challenge, you must create a bot which plays the centipede game. In the centipede game, there are two players, and two piles of coins. One pile is 1/4 the size of the other. Each turn,...

Anonymous

Probably

Anonymous

Just put in variables for the variable values

New Sandboxed Posts

07:36

0

A: Sandbox for Proposed Challenges

Play the centipede game king-of-the-hill (please note that I need to learn how to make a controller) In this challenge, you must create a bot which plays the centipede game. In the centipede game, there are two players, and two piles of coins. One pile is 1/4 the size of the other. Each turn,...

Sp3000

07:47

@orlp As far as I can tell, it's like going from f(1) = 1, f(2) = 4, f(3) = 9 and interpolating a quadratic to get f(0) = 0? But in this case a degree 9 poly

orlp

if I did everything correctly

a_0 = 10*f_1 - f_10 - 45*f_2 + 120*f_3 - 210*f_4 + 252*f_5 - 210*f_6 + 120*f_7 - 45*f_8 + 10*f_9
a_1 = -4861*f_1/252 + 7129*f_10/2520 + 6121*f_2/56 - 6541*f_3/21 + 6751*f_4/12 - 6877*f_5/10 + 6961*f_6/12 - 1003*f_7/3 + 3533*f_8/28 - 789*f_9/28
a_2 = 79913*f_1/5040 - 6515*f_10/2016 - 115923*f_2/1120 + 400579*f_3/1260 - 71689*f_4/120 + 5985*f_5/8 - 461789*f_6/720 + 22439*f_7/60 - 39867*f_8/280 + 161353*f_9/5040
a_3 = -663941*f_1/90720 + 4523*f_10/2268 + 264767*f_2/5040 - 433739*f_3/2520 + 728587*f_4/2160 - 62549*f_5/144 + 273431*f_6/720 - 242639*f_7/1080 + 435893*f_8/5040 - 197741*f_9/10080

is that the generic solution

(but we only need a_0)

so let's try 10*f_1 - f_10 - 45*f_2 + 120*f_3 - 210*f_4 + 252*f_5 - 210*f_6 + 120*f_7 - 45*f_8 + 10*f_9 out

Sp3000

Er... that's an unnecessarily complicated way to go about it I think

Anonymous

Yeah, sum(a*b for a,b in zip((10, -45, 120, -210, 252, -210, 120, -45, 10, -1),map(int,input().split())) should work

orlp

seems that that did it

[10,-45,120,-210,252,-210,120,45,10]

is there some significance to this sequence?

Sp3000

Binomial coefficients with alternating signs would be my first guess

orlp

07:52

seems pascal triangle-esque

yep

oeis.org/…

Sp3000

Hmm now I'm not sure whether the direct approach with your coefficient list is better or whether successive differences is better

orlp

successive differences?

Sp3000

08:08

As in f=lambda L:L>[]and L[0]-f(map(int.__sub__,L[1:],L[:-1])) (badly golfed)

orlp

also, I'm new to anarchy code golf, why does it give multiple test cases that your program must solve at once?

@Sp3000 Im still confused

Sp3000

in Code Golfer's Corner, 15 hours ago, by xnor

is there a reason that anarchy challenges usually have multiple lines in input in each test case?

orlp

my direct form is not the simplest solution?

Sp3000

shrugs

orlp

I don't understand your solution Sp

can you write it non-golfed?

Sp3000

08:09

Easier to give an example, e.g. the quadratic from before

[1, 4, 9] -> [3, 5] -> [2] taking differences

Then starting from the end, 3-2 = 1, and then 1-1 = 0

orlp

now I'm even more confused

like, how is repeated subtractions a solution for this problem?

Sp3000

It's like doing discrete derivatives then interpolating

DerpfacePython

we should have banner art for PPCG.

Anonymous

@orlp Divided differences a la Lagrange interpolation

DerpfacePython

Quoi?

xsot

08:16

7

Q: Implement the Method of Finite Differences

The Method of Finite Differences is a technique used to find the next term in a sequence of numbers, given that the sequence is governed by consecutive values of a certain polynomial. Given a list of n terms, the Method will be able to determine the degree of the polynomial, which is a maximum of...

code-golf math number

Sp3000

^^ thanks xsot, was having trouble explaining

(also forgot that it had an actual name)

xsot

I didn't know this was a thing actually

orlp

why does this give a_0 though

Leaky Nun

CMC: 10 programs for each digit without using any digit (0x30 to 0x39 inclusive) in the source code.

Sp3000

It's to do with the fact that all the values given are for x=1..9 (i.e. evenly spaced with interval 1)

You could get f(-1) with a repeated application of the second half of the algorithm

xsot

08:19

It helps to consider simpler polynomials

Sp3000

(for example)

DerpfacePython

Pop-con: build the banner for PPCG in 1kb or less?

Make-your-own banner?

Leaky Nun

Pyth:
Z
hZ
hhZ
hhhZ
hhhhZ
hhhhhZ
ttttT
tttT
ttT
tT

DerpfacePython

That way we could have a banner for PPCG and a reasonable pop-con.

Anonymous

52

Q: No strings (or numbers) attached

If you like this, you may also like Official Dyalog APL 2016 Year Game. Make 12 snippets/expressions, in the same language, that result in the numbers 0 through 10, and 42 respectively, but without writing any literal numeric, string, or character data. Build-in data, like PI() and ALPHABET()...

code-golf number restricted-source generation multiple-holes

orlp

08:21

@LeakyNun for C, 'a'^'Q', 'b'^'Q', ...

Leaky Nun

@mego close the challenge on main as dup?

@orlp you forgot main and puts

orlp

@LeakyNun irrelevant

just wanted to post the solution

not the boilerplate :P

Leaky Nun

alright

orlp

@Sp3000 I think it's really cool that my two solutions for Fractal X and Fractal Plus only differ by 4 characters

xsot

08:39

@orlp It's to avoid this kind of scenario: golf.shinh.org/p.rb?read+english+numbers

orlp

@xsot you can make many test cases without having them in one invocation of your program

xsot

The site restricts the problem setter to 3 test cases at most.

Leaky Nun

09:02

@orlp for C use the first argument of main instead

βετѧ Λєҫαγ

Morning all

CMC: What's the best pyramid you can make?

retina.tryitonline.net/…

Leaky Nun

programming quiz: what is the value produced by the following snippet? (dont cheat)

int a=0; (a++)+(++a)+(a++);

βετѧ Λєҫαγ

6

Leaky Nun

i think it is 5 instead

βετѧ Λєҫαγ

(0+1)+(1+1)+(1+1)

Oh yeah, that's five :P

Lynn

09:10

It’s undefined behavior.

Releasing Helium Nuclei

@LeakyNun i think answer is 3

RTL

a++ increments a but reurns the initial value. ++a increments a and returns the incremented value. It all happens RTL

Anonymous

^

Anonymous

It depends on the compiler. gcc evaluates LTR, MSVC evaluates RTL.

Releasing Helium Nuclei

@LeakyNun putchar('D'-' ') ... putchar('M'-' ');

Anonymous

Unless I got that backwards again

Releasing Helium Nuclei

09:20

@Mego i thought gcc is rtl too, it isn't?

Anonymous

Oh wait it's RTL for gcc and LTR for MSVC (and clang)

Releasing Helium Nuclei

Trying to find a good source w8

Anonymous

Actually, as of C++17, it's no longer UB. The standard states that the compiler is allowed to choose any evaluation order (indeterminate order).

Anonymous

en.cppreference.com/w/cpp/language/eval_order

Releasing Helium Nuclei

The C Standard states in any UB compiler should choose what happens, what is the difference?

ΛεγίωνΜάμμαλϠΨΠʹ

10:10

Question: The C Standard says that compilers must specify their UB, but where are these specifications stored?

xsot

@orlp 80: main(x){for(x<<=16;x--;)x&x/2&'UU'||x%256*putchar((x^x>>8)&85?32:88)||puts("");}‌

orlp

@xsot hah, didn't think of multi-letter constants

should I post that?

or

Sp3000

Post as orlp (xsot) or the other way around?

However the system works

xsot

no need to credit me

it's a common trick

looks like you're still behind tails by one byte

orlp

@xsot ?

oh he posted a new answer then

@xsot wait a sec he's doing something weird

the statistics don't add up

xsot

10:19

The missing bytes are whitespace characters

orlp

the only way I can see improving on my golf is the way you handle newlines

like, my answer is already so heavily golfed...

Sp3000