Code Golf: Duplicate Character Removal in String

Question

The challenge: The shortest code, by character count, that detects and removes duplicate characters in a String. Removal includes ALL instances of the duplicated character (so if you find 3 n's, all three have to go), and original character order needs to be preserved.

Example Input 1:
nbHHkRvrXbvkn

Example Output 1:
RrX

---

Example Input 2:
nbHHkRbvnrXbvkn

Example Output 2:
RrX

(the second example removes letters that occur three times; some solutions have failed to account for this)

(This is based on my other question where I needed the fastest way to do this in C#, but I think it makes good Code Golf across languages.)

Answer 1

Javascript 1.8

s.split('').filter(function (o,i,a) a.filter(function(p) o===p).length <2 ).join('');

or alternately- similar to the python example:

[s[c] for (c in s) if (s.split("").filter(function(p) s[c]===p).length <2)].join('');

Answer 2

Ruby — 61 53 51 56 35

61 chars, the ruler says. (Gives me an idea for another code golf...)

  puts ((i=gets.split(''))-i.select{|c|i.to_s.count(c)<2}).join
+-------------------------------------------------------------------------+
||    |    |    |    |    |    |    |    |    |    |    |    |    |    |  |
|0         10        20        30        40        50        60        70 |
|                                                                         |
+-------------------------------------------------------------------------+
  gets.chars{|c|$><<c[$_.count(c)-1]}

... 35 by Nakilon

Answer 3

TCL

123 chars. It might be possible to get it shorter, but this is good enough for me.

proc h {i {r {}}} {foreach c [split $i {}] {if {[llength [split $i $c]]==2} {set r $r$c}}
return $r}
puts [h [gets stdin]]

Answer 4

Scala

54 chars for the method body only, 66 with (statically typed) method declaration:

def s(s:String)=(""/:s)((a,b)=>if(s.filter(c=>c==b).size>1)a else a+b)

Answer 5

C# (53 Characters)

Where s is your input string:

new string(s.Where(c=>s.Count(h=>h==c)<2).ToArray());

Or 59 with re-assignment:

var a=new string(s.Where(c=>s.Count(h=>h==c)<2).ToArray());

Answer 6

another APL solution

As a dynamic function (18 charachters)

{(1+=/¨(ω∘∊¨ω))/ω}

line assuming that input is in variable x (16 characters):

(1+=/¨(x∘∊¨x))/x