String Concatenation

Question

The Challenge

Given two strings containing only lowercase letters and no spaces, the result should be the shorter string, followed by an underscore, followed by the longer string with the first instance of a character removed for each character it contains that is in the shorter string.

You can assume the strings will always be different lengths.

Test Cases:

sale
salinewater
Result: sale_inwater (only the first 'a' in salinewater is removed)
jostling
juggle
Result: juggle_ostin (juggle is the shorter string)
juggle
juggler
Result: juggle_r (a 'g' is removed for every 'g' in the shorter string)

Rules

This is code-golf, so shortest answer in bytes wins!

• Peter Taylor: What does "remove the first occurrence" mean when the shorter string has duplicate characters?
• xnor: Four days is very short to pick a winner, I'd suggest at least a couple of week at minimum. Also, in the future I'd suggest first posting to the Sandbox where challenges can be clarified and improved before going live.
• Ajay: smaller string is shorter string......sorry for my bad english
• PurkkaKoodari: What should the output for juggle juggler be? juggle_r (remove for each character instance) or juggle_gr (remove for each distinct character)?
• Luis Mendo: @Pietu1998 That's a good point. We should put this on hold until clarified

Answer 1

Pyth, 13 bytes

++hAlDQ\_.-HG

Try it online.

Answer 2

JavaScript (ES6), (削除) 78 (削除ここまで) (削除) 75 (削除ここまで) 69 Bytes

const 
 g=(x,y)=>x[y.length]?g(y,x):[...x].map(c=>y=y.replace(c,''))&&x+'_'+y
;
console.log(g.toString().length + 2); // 69
console.log(g('sale', 'salinewater')) // sale_inwater
console.log(g('juggle', 'juggler')) // juggle_r
console.log(g('jostling','juggle')) // juggle_ostin

Breakdown

x[y.length]?g(y,x): \\ Make sure that x is the shorter string
[...x] \\ Spread string in array of characters
.map(c=>y=y.replace(c,'')) \\ For each character remove its first occurence in y
&&x+'_'+y \\ Concat x and changed y 

Answer 3

Haskell, (削除) 56 (削除ここまで) 55 bytes

import Data.List
x%y|(0<$y)<(0<$x)=y%x|z<-y\\x=x++'_':z

-1 byte thanks to @xnor

• xnor: You can cut a byte by binding y\\x for the 0<1 otherwise guard.
• Damien: filter(`notElem`x)y is shorter than y\\x with import
• dianne: @Damien I think that would remove all occurrences of elements of x, not just the first ones.
• Damien: Oh, yes you are right.

Answer 4

Java 7, 262 bytes

import java.util.*;String c(String z,String y){int i=0,l=y.length();if(z.length()>l)return c(y,z);List x=new ArrayList();for(;i<l;x.add(y.toCharArray()[i++]));for(Object q:z.toCharArray())x.remove(q);String r="";for(i=0;i<x.size();r+=x.get(i++));return z+"_"+r;}

Can probably be golfed some more by just using arrays without the lists..

Ungolfed & test cases:

Try it here.

import java.util.*;
class M{
 static String c(String z, String y){
 int i = 0,
 l = y.length();
 if(z.length() > l){
 return c(y, z);
 }
 List x = new ArrayList();
 for(; i < l; x.add(y.toCharArray()[i++]));
 for(Object q : z.toCharArray()){
 x.remove(q);
 }
 String r = "";
 for(i = 0; i < (x.size()); r += x.get(i++));
 return z+"_"+r;
 }
 public static void main(String[] a){
 System.out.println(c("sale", "salinewater"));
 System.out.println(c("jostling", "juggle"));
 System.out.println(c("juggle", "juggler"));
 }
}

Output:

sale_inwater
juggle_ostin
juggle_r

Answer 5

Java 8, 156 Bytes

String a(String x,String y){int l=x.length(),m=y.length();String b=l>m?x:y,s=m<l?y:x;for(char c:s.toCharArray()){b=b.replaceFirst(""+c,"");}return s+"_"+b;}

This can probably be golfed some more.

Ungolfed & test cases

interface A {
 static String a(String x,String y){
 int l=x.length(),m=y.length();
 String b=l>m?x:y,s=m<l?y:x;
 for(char c:s.toCharArray()){
 b=b.replaceFirst(""+c,"");
 }
 return s+"_"+b;
 }
 
 static void main(String[]a) {
 System.out.println(a("sale","salinewater"));
 System.out.println(a("jostling","juggle"));
 System.out.println(a("juggle","juggler"));
 }
}

Answer 6

Ruby, 65 bytes

->a,b{a,b=b,a if a.size>b.size;a.chars.map{|e|b.sub!e,""};a+?_+b}

ungolfed

->a, b{
 a, b = b, a if a.size > b.size
 a.chars.map { |e|
 b.sub! e, ""
 }
 a + ?_ + b
}

61 bytes(in case the argument is an array of strings)

->a{a.sort_by!(&:size);a[0].chars.map{|c|a[1].sub!c,""};a*?_‌​}

Thank you, m-chrzan!

• m-chrzan: gsub! doesn't work here - you're supposed to remove the first occurance of each letter. Fortunately, sub!, which does exactly that, is a byte shorter.
• m-chrzan: Also, I think you need to name the lambda in this case, since you do end up calling it. However, doing a,b=b,a if a.size>b.size to exchange the strings is non-recursive, and saves you another byte.
• cia_rana: @m-chrzan Oh, I didn't observe carefully the question. Thanks!
• m-chrzan: 61 bytes, input as an array of strings: ->a{a.sort_by!(&:size);a[0].chars.map{|c|a[1].sub!c,""};a*?_}
• cia_rana: @m-chrzan Great! I added your answer.

Answer 7

PHP, 154 Bytes

list($f,$s)=strlen($b=$argv[2])<strlen($a=$argv[1])?[$b,$a]:[$a,$b];foreach(str_split($f)as$x)$s=preg_replace("#(.*?)".$x."(.*)#","1ドル2ドル",$s);echo$f."_$s";

Instead of $s=preg_replace("#(.*?)".$x."(.*)#","1ドル2ドル",$s); you can also use if($z=strstr($s,$x))$s=strstr($s,$x,1).substr($z,1);

Answer 8

R, 161 bytes

This turned out to be much longer than I expected, albeit, string manipulation is usually tedious in R. I feel that this should easily be golfable by just using another approach.

function(x,y){s=strsplit;if(nchar(x)>nchar(y)){v=y;w=x}else{v=x;w=y};v=s(v,"")[[1]];w=s(w,"")[[1]];j=0;for(i in v){j=j+1;if(i==w[j])w[j]=""};cat(v,"_",w,sep="")}

Ungofled

function(x,y){
 s=strsplit # alias for stringsplit
 if(nchar(x)>nchar(y)){v=y;w=x} # assign v/w for the short/long strings
 else{v=x;w=y}
 v=s(v,"")[[1]] # split short string into vector
 w=s(w,"")[[1]] # split long string into vector
 j=0
 for(i in v){ # for each char in short string, check
 j=j+1 # if is equal to corresponding char in
 if(i==w[j])w[j]="" # long, replace long with "" if true
 }
 cat(v,"_",w,sep="") # insert _ and print
}

Answer 9

Python 2, (削除) 81 (削除ここまで) 72 bytes

a,b=sorted(input(),key=len)
for c in a:b=b.replace(c,"",1)
print a+"_"+b

Try it online

• dianne: I think you can save 9 bytes by replacing the first two lines with a,b=sorted(input(),key=len)

Answer 10

Scala, 78 bytes

def f(a:String,b:String):String={if(a.size>b.size)f(b,a)else
a+"_"+(b diff a)}

Explanation:

def f(a:String,b:String):String={ //define a method f which has two String parameters and returns a String
 //(because it's recursive, scala can't figure out the return type)
 if (a.size > b.size) //make sure that a is the shorter string
 f(b, a)
 else
 a+"_"+(b diff a) //`b diff a` removes all elements/chars of a from b
}