Me thinks there aren't enough easy questions on here that beginners can attempt!
The challenge: Given a random input string of 1's and 0's such as:
10101110101010010100010001010110101001010 Write the shortest code that outputs the bit-wise inverse like so:
01010001010101101011101110101001010110101 jkms!s
Takes input as a string. New at this so it probably isn't optimal but the shortest pyth one here so far!
1 INPUT A$ 2 PRINT A$ 3 FOR I=1 TO LEN A$ 4 PRINT NOT VAL A$(I); 5 NEXT I This technique iterates over each byte of the string, taking it's numeric value and printing the NOT equivalent. In ZX81 terms, NOT 1 is 0 and NOT 0 is 1. RUN the program and enter your binary string, followed by NEW LINE (or the Enter key).
Simple test case shown below.
Performs 3 substitutions: 0 -> 5, 1 -> 0, 5 -> 1
=SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1,0,5),1,0),5,1) For fun, replacing the third substitution (5 -> 1) eith a /5 works for input where first character is 0. But for others, need to pad with for length. Resulting in 59 bytes:
=TEXT(SUBSTITUTE(SUBSTITUTE(A1,0,5),1,0)/5,REPT(0,LEN(A1))) 
while((n<=${#1}));do case "${1:$n:1}" in 0)printf 1;;1)printf 0;; esac;n=$((n+1));done 
[N S S N _Create_Label_LOOP][S S S T T S S S T N _Push_49][S N S _Duplicate_49][S N S _Duplicate_49][T N T S _Read_STDIN_as_character][T T T _Retrieve][T S S T _Subtract][S N S _Duplicate][N T S S N _If_0_Jump_to_Label_1][S S S T N _Push_1][T S S T _Subtract][N T S T N _If_0_Jump_to_Label_0][N N N _Exit][N S S T N _Create_Label_0][S S S T N _Push_1][N S S S N _Create_Label_1][T N S T _Print_integer_to_STDOUT][N S N N _Jump_to_Label_LOOP] Letters S (space), T (tab), and N (new-line) added as highlighting only.
[..._some_action] added as explanation only.
Since Whitespace can only take input as integer or character, we must add a trailing character (other than 0 or 1; like a newline, space, a letter, etc.) to indicate we're done with the input-string after reading it character by character.
Try it online (with raw spaces, tabs and new-lines only).
Example run: input = 100
Command Explanation Stack Heap STDIN STDOUT NSSN Create Label_LOOP [] SSSTTSSSTN Push 49 [49] SNS Duplicate 49 [49,49] SNS Duplicate 49 [49,49,49] TNTS Read STDIN as character [49,49] {49:49} 1 TTT Retrieve [49,49] {49:49} TSST Subtract (49-49) [0] {49:49} SNS Duplicate 0 [0,0] {49:49} NTSSN If 0: Jump to Label_1 [0] {49:49} NSSSN Create Label_1 [0] {49:49} TNST Print to STDOUT as integer [] {49:49} 0 NSNN Jump to Label_LOOP [] {49:49} SSSTTSSSTN Push 49 [49] SNS Duplicate 49 [49,49] SNS Duplicate 49 [49,49,49] TNTS Read STDIN as character [49,49] {49:48} 0 TTT Retrieve [49,48] {49:48} TSST Subtract (49-49) [1] {49:48} SNS Duplicate 0 [1,1] {49:48} NTSSN If 0: Jump to Label_1 [1] {49:48} SSSTN Push 1 [1,1] {49:48} TSST Subtract (1-1) [0] {49:48} NTSTN If 0: Jump to Label_0 [] {49:48} NSSTN Create Label_0 [] {49:48} SSSTN Push 1 [1] {49:48} NSSSN Create Label_1 [1] {49:48} TNST Print to STDOUT as integer [] {49:48} 1 NSNN Jump to Label_LOOP [] {49:48} SSSTTSSSTN Push 49 [49] SNS Duplicate 49 [49,49] SNS Duplicate 49 [49,49,49] TNTS Read STDIN as character [49,49] {49:48} 0 TTT Retrieve [49,48] {49:48} TSST Subtract (49-49) [1] {49:48} SNS Duplicate 0 [1,1] {49:48} NTSSN If 0: Jump to Label_1 [1] {49:48} SSSTN Push 1 [1,1] {49:48} TSST Subtract (1-1) [0] {49:48} NTSTN If 0: Jump to Label_0 [] {49:48} NSSTN Create Label_0 [] {49:48} SSSTN Push 1 [1] {49:48} NSSSN Create Label_1 [1] {49:48} TNST Print to STDOUT as integer [] {49:48} 1 NSNN Jump to Label_LOOP [] {49:48} SSSTTSSSTN Push 49 [49] SNS Duplicate 49 [49,49] SNS Duplicate 49 [49,49,49] TNTS Read STDIN as character [49,49] {49:10} \n TTT Retrieve [49,10] {49:10} TSST Subtract (49-10) [39] {49:10} SNS Duplicate 39 [39,39] {49:10} NTSSN If 0: Jump to Label_1 [39] {49:10} SSSTN Push 1 [39,1] {49:10} TSST Subtract (39-1) [38] {49:10} NTSTN If 0: Jump to Label_0 [] {49:10} NNN Exit program [] {49:10} Fully portable (not just one or two character encodings).
f(char*s){for(;*s;)*s++^='0'^'1';} Output is in-place modification of the string.
A less portable version would use a simple number in place of the expression '0'^'1' - e.g. 1 for ASCII or EBCDIC - saving up to 6 bytes.
#include<stdio.h> int main(void) { char s[] = "10101110101010010100010001010110101001010"; f(s); printf("%s\n", s); } 
1 for ASCII or EBCDIC systems, but that's not fully portable. \$\endgroup\$ iSBql[n1~-o]~*; i # Read input as string. S # Push array of characters in the string. B # Push every character in the array to the stack. q # Reverse the stack. l # Push the size of the stack. [ ] # Push a function that does the following: n # Convert top of stack to int. 1~- # Push 1, swap the top two items in the stack and subtract them. This takes a character x in the input string to 1-x, resulting in the bit negation. o # Output the top item of the stack ~ # Swap the top two items in the stack. * # Call the above function the same number of times as length of the input string. (That is, for each bit in the input string, negate the bit and output it.) ; # Exit Shell builtins only: specifically, the XOR operator ^.
29 bytes: <<<$[1^1]${1:+`$0 ${1:1}`} recursion, by @GammaFunction 30 bytes: for X (${(s::)1})printf $[1^X] more efficient for, by @GammaFunction 32 bytes: for X in ${(s::)1};printf $[1^X]
35 bytes: echo $[1^${1:0:1}]${1:+`$0 ${1:1}`} recursion, by @GammaFunction 44 bytes: for((;i<${#1};i++));{ printf $[1^${1:i:1}];}
${:+recursion}. \$\endgroup\$ for X (...) form for 30 in Zsh \$\endgroup\$ fork calls get denied on TIO. \$\endgroup\$ 2a2x1v4a8m2x0v1x0f1a1o1f0x1x1f1r3x1v2e3x0v0e1s1o1f0x1x2f0a0x1f Works for any input file of 1's and 0's terminated with the control character STX (U+0002).
Explanation (with 0x commands removed)
2a2x1v # Set variable 1 equal to 2 4a8m2x0v # Set variable 0 equal to 48 1x0f1a1o1f # Function 0 # Add 1 to the register, output, then jump to function 1 1x1f1r3x1v2e3x0v0e1s1o1f # Function 1 # Read a byte of input # Jump to function 2 if it equals variable 1 # Jump to function 0 if it equals variable 0 # Otherwise, subtract 1 from the register, output, # then jump back to the start of function 1 1x2f0a # Function 2 # Add 0 to the register 1f # Call function 1 
12 22467800860124070178830737520017462583858242261688818083563967964459492073122807697499205500520814270057390910850070898023779372337845606451434999597324513116009103282793138363889251070541548956324245082329674394635061703600124082725719347051922338244963555154324370355238030226191755446700141538448744882828401289257105544925638425778005923480537339123570198316859318125063896435356052960878798108984454300034802385262580209301524236136248719519921946031828718409466542238635588879942564163080889109125277745199171883349061520869997942949639546109688688788190940395919772174262841234098191606390237829497693620421210677789981161937899626045826080802574655497452130041254940986107805698757014260882449573944556602129769737703315763962652354056343895230431267996034382053925203053307001003333804173344801825634791820695141553355621023990400711189803634409496082889140704419749000824286397618093636247662749951187708752873519950104578968340972361618524412325645098713699731021088671725575084245344751522649567245480821120339220564646068943031946783303903697367253955714044444736783957222575572241319818457276409266126595415669073513253183989135440889608714964831521757016620819816850763183162405901035026179418588534822021105457990128662024405359920540011554379532044740831623941815066395865241509740805855343347903491296220782048364612164349265833607844707347159345067371895976293721572188715573401930387350648051542907586789168439477137453524755084958277596405623536912666957589117645881846750438246766165234099806368247856450957646185589082789378547512134409783416060602945874310445999221638049305359530033182401798760305340764937308446248612494477798147335809113299917339976366532774445821809050635734106638274070832257786599315353165493685027605339636316348551394743274112960759253605959515456316478044100123168731682979291374569338572092082869123150387567271191092971638844368321984656886356084605909222030710150000407927489274727063860328145859688080273381880596439423213732909155412724144303878876832255238035073247552082203299616735975900731438704855017567941085339636443620043767639365385673296669965015825191217275207514003602363380064736873151800792178445714348743862550536432711191527537777366511426388278812825671029910854980928682139046501881451902927544724305377340163929216935010743857978836424566071713806944632017276688837315532946743339777915616030011161708954637903288482182308670771005462983742584744344066707662057998285468364681750429465060696832417939697844369858677491150502866685111618816518160802785248209223095658989030839275159107736257541077894710268795690490482316124636074318996932638195319298458661969220607094970584356214121664089841491446209143755531268896976923041463145479413553581327439998726678121104922190297288358873060196647710463668580909699483989882954140817314685815779877890795712718361623431063616953603383264989936053474641614569529053703569694229770237259956181704387417633362063048253194547238628479951576197180647512354097114011449776247632199450163435658817379247320758050414702476804424429759571774687799269847272241040125929986561154071306898735707411802043172870573801610582124052361577796587449450980584367871604033018651000439099472710719881306790290886915898325194141014611846079395667807264562687901178526268969175193051163108905837484413417816154510711926841899863006227166207619380521870269028440296101561963248505036429083164400024679203296550171382565396820939898890114978768872643479708314697168816959694732131149657059289619022081777426733646802338248337315031956161258755974424581432365955447254124547801478393685789570178512768654602326030764253268669713151354485782078002288517388185165706102804594623909510752146365156058948091625484531645749465785838573681651816640209540090471551546428418684230905961729447735111300809970327136013512273479286642147001855525584783017763430816620169651297763121245380125111624755448069360703085235290573427681024676161302183767200167011805149778397302405685676191974385732998259279459936937214011 Doesn't work on TIO.
x->replace(x,'0'=>'1','1'=>0) Julia also has the operator ~ for bitwise not:
julia> x=0b10101110101010010100010001010110101001010 0x0000015d5288ad4a julia> bitstring(x) "0000000000000000000000010101110101010010100010001010110101001010" julia> bitstring(~x) "1111111111111111111111101010001010101101011101110101001010110101" ``` 
-16, 61 bytes-1 96 -1 87 22 -1 87 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 TIO doesn't allow passing arguments to the compiler so I called the program manually.
16-bit mode is not very useful outside of minimizing offsets because self-modifying code is unable to encode a negative offset. This is because in all word sizes, the offsets are read stored in an int32 array and they are not properly sign extended unless the source was sign extended.
So for example, if I do
.include lib.bbj .copy A, B A:0 B:-1 The result will be this:
A:65535 B:-1 The code expects a string followed by a newline.
Explained:
# Read bit 0 from stdin to "x" L:-1 i:x # Store bit 1 to bit 7 of the jump offset of this instruction. # When '\n' (00001010), bit 1 will be set and instead of jumping to the next # instruction (96), it will jump to e (224) -1 j'7 j:? # Bits [7:6] of i are 01. When the first bit of stdin is copied here, # it will either target i'6 or i'7. # It basically becomes {1, 0}[i], flipping the bit. x:i'6 -1 # When the IP interprets e, it sees -1, 240, -1, which exits. # -1 240 -1 j'7 e:-1 # Copy the rest of stdin to stdout -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 # Loop -1 -1 L This code compiles to this.
-1 96 48 # 1111111111111111 0000000001100000 0000000000110000 -1 87 96 # 1111111111111111 0000000001010111 0000000001100000 22 -1 144 # 0000000000010110 1111111111111111 0000000010010000 87 -1 192 # 0000000001010111 1111111111111111 0000000011000000 -1 -1 240 # 1111111111111111 1111111111111111 0000000011110000 -1 -1 288 # 1111111111111111 1111111111111111 0000000100100000 -1 -1 336 # 1111111111111111 1111111111111111 0000000101010000 -1 -1 384 # 1111111111111111 1111111111111111 0000000110000000 -1 -1 432 # 1111111111111111 1111111111111111 0000000110110000 -1 -1 0 # 1111111111111111 1111111111111111 0000000000000000 
B, 3 bytes1Æ^ Inspired by Dennis's GolfScript answer.
The B flag does most of the heavy-lifting here.
# Implicit input. The B flag converts the # input string to a list of codepoints. 1Æ^ # Compute the bitwise XOR of each codepoint # with 1, so 48 -> 49 and 49 -> 48 # Implicit output. The B flag converts the # integer list to a string. 
_ Try it online! Beats all other answers. Takes I/O as a list of bits.
_ # full program _ # logically negate... # (implicit) each element of... # implicit input # implicit output 
print(readLine map(c=>"10"(c&1))) 
$*[0].each_char{|x|p x==?0?1:0} 
$*[0].each_char{|x|p x==?0?1:0} \$\endgroup\$ (($args-split''-ne'')|%{1-bxor$_})-join'' Explanation:
It reads the input and splits it to turn it into an array. Then it iterates through every element of the array and uses the bitwise exclusive or to turn 1 to 0 and 0 to 1, and then joins the result and prints it to console...
@echo off&setlocal enabledelayedexpansion&set l=-1&set s=%~1&set o=%~1 :c if defined s set/al+=1&set s=%s:~1%&goto c for /l %%a in (%l%,-1,0)do set/p=!o:~%%a,1!<nul Could be cut down a bit by using Powershell to get the length of the input - then again, it could be cut down a lot by using a different language.
r=str.replace r(r(r(input(),'1','a'),'0','1'),'a','0') It's not as short as some of the other ones, but it takes a different approach.
Where $s is the string:
str_replace(array(1,0,2),array(2,1,0),$s) This works because the str_replace() function is just a loop when given an array. This works like this:
1 with 20 with 12 back to 0edit thanks to cfrick's insightful comment:
print args[0].tr("01","10") previous:
args[0].each{print it=="1"?0:1} 
tr. e.g. b.tr('01','10') \$\endgroup\$ a=prompt() for(b='',r=/./g;c=r.exec(a);b+=c^1); alert(b) Three solutions here, all of which assume that the argument is being passed as a string in a variable "b". If it is being passed in another format (as I think some of the other solutions here assume), shorter solutions are possible.
Method 1, using bitwise operator for 64 char
StringJoin[ToString[BitNot[#] + 2] & /@ ToExpression[Characters@b]] Method 2 using If/Then for 45 char
StringJoin[If[# == "0", "1", "0"] & /@ Characters@b] Method 3, operating directly on the string, for 34 char
StringReplace[b, {"0" -> "1", "1" -> "0"}] I suspect some Mathematica wizard is going to breeze in here and do it in 15 bytes.
→ is 3 bytes. \$\endgroup\$ main(c){for(;c=~getchar();putchar(~c^1));} 
$<.each_char{|i|print (i.ord-1).chr.gsub"/","1"} Not the shortest, but somewhat interesting
