Reverse String

[johnbasedow]

I present you with the challenge of making the smallest program that will reverse a string.

The one I'm working on is 50 bytes including title, but I KNOW someone can go smaller. Much smaller.

Here's what I have so far:

PROGRAM:A
:" (one space)/->/Str1
:Input Str2
:For(X,length(Str2),1,-1
:Str1+sub(Str2,X,1/->/Str1
:End

[Harrierfalcon]

Admin, someone, merge this into the 83 Basic Brain Teaser?

Anyways, I've come up with 50 bytes--input string is in Str1, output string in Ans. 50 bytes is the program minus the length of the title.

Try not to doublepost unless needed. Unless the topic is almost dead, just edit your post.

And, generally speaking, these challenges are made to be as small as possible--i.e. the input string probably should be in Ans, and the output probably should be in Ans as well. Don't try and add effects. That said, yours technically doesn't work, because there is a space preceding the output string.

[johnbasedow]

[DarkerLine]

My current attempt is 43 bytes when you subtract the length of the title (input and output both in Ans)

[Weregoose]

[DarkerLine]

Oh. I didn't use a second string. And I don't have a filler character.

[thornahawk]

This particular one is almost twice the size, but it seems to dent the memory less if the string is long:

(highlight below)

Ans→Str0
length(Ans)–1→L
For(K,1,L
sub(Str0,K+1,1)+sub(Str0,1,K
If K<L
Ans+sub(Str0,K+2,L–K
Ans→Str0
End
Str0


thornahawk

[johnbasedow]

[DarkerLine]

suppose the string we start with is "HELLO".

We begin by adding the SECOND (I=1 so 2I=2) character of the string to the beginning, to get "EHELLO".

Then we add the fourth (I=2 so 2I=4) character of the current string, which was the THIRD character of the original string: now we have "LEHELLO"

Then the sixth (I=3 so 2I=6) character of the current string, which was the FOURTH character of the original string: now we have "LLEHELLO"

Finally, we add the 8th character, which was originally the fifth, to get "OLLEHELLO".

(In general, when we're adding the 2Ith character of the current string, we've already added I-1 characters to the front, so we're really adding the I+1th character of the original string)

The first 5 characters of the string are the original string backwards - "OLLEH", so we take those 5 characters and get our result. Notice that after we exit the loop, I is the next value we'd be on if we continued - the last value of I we took was 4, so I is 5 now, which is just the length of the string.

Does this help?

[adriweb]

it helped me !
Thanks !

(you're a so great programmer ^^ )

[jwymbs23]

So in these uberoptimisations, do we not leave in the input functions?

[JoostinOnline]

You should, but people cheat sometimes and leave them out.

[DarkerLine]

Well, usually the idea is that you pass in the argument in Ans. I mean, you can't really optimize an "Input" or "Prompt" command, so it doesn't really matter.

[JoostinOnline]

[DarkerLine]

That's never been an issue in those cases, as both people were using the same conventions every time.