Shortest Program to Sort a List of numbers into Odd and Even Category

Question

In the New Modern Times, when Charlie Chaplin encounters a computer, he is employed in the sorting Yard, as a validator to determine if the workers are correctly sorting the items. The Items in question are packets of marbles. Packets with Odd number of Marbles are stacked in the Red Basket and Packets with Even Number of Marbles are stacked in the Blue Basket.

Charlie Chaplin is supposed to punch the program that would validate if there is any anomaly in the sorting procedure. Mack Swain his immediate Boss, shares an algorithm which he needs to code.

Algorithm

L = List of Marble packets that's already sorted
L_ODD = List of packets with Odd Number of Marbles
L_EVEN = List of packets with Even Number of Marbles
Check_Digit = √(ΣL_ODD² + ΣL_EVEN²)

His Job is to determine the Check_Digit and match it with what ever value his Boss calculates.

Charlie Chaplin during his lunch hours, were able to sneak to Mack Swain's drawer and determine, that his drawer has a single card with punches on the first 46 32 columns (which means Mack was able to write a program with only 46 32 characters).

Charlie Chaplin would now need the help of all the code ninja's to write a program with as few lines as possible. He also announces a bonus of 50 points, if someone can come up with a program which is shorter than his Boss.

Summary

Given a list/array/vector of positive numbers (odd and even), you need to write a function, which would accept the array(int [])/vector<int>/list and calculate the root of the sum of the squares of the sums of odd and even numbers in the list.

The Size of the program is the size of the body of the function, i.e. excluding the size of the function signature.

Example

List = [20, 9, 4, 5, 5, 5, 15, 17, 20, 9]
Odd = [9, 5, 5, 5, 15, 17, 9]
Even = [20, 4, 20]
Check_Digit = √(ΣOdd² + ΣEven²) = 78.49203781276162

Note, the actual output might vary based on the implementation's floating point precision.

Score

Score is calculated as Σ(Characters in your Program) - 46.Score is calculated as Σ(Characters in your Program) - 32. Apart from the regular upvoting from the community, the lowest negative score would receive an additional bonus of 50 points.

Edit

1. The offset that was used to calculate the Score has been changed from 46 to 32. Note, this would not affect the leader-board/ bounty eligibility or invalidate any solution.

Verdict

After a gruesome duel between the Ninjas, Mr. Chaplin received some wonderful answers. Unfortunately few of the answers tried to take undue advantage of the rule and was not very useful. He actually wanted a fair duel and answers where the logic was coded within the function signatures would eventually mean the function signature is an integral part of the solution. Finally, Ninja FireFly was the clear winner and awarded him the bonus he well deserves. Leaderboard (updated every day)

╒══════╤═════════════════╤══════════════╤═════════╤════════╤═══════╕
├ Rank │      Ninja      │   Dialect    │ Punches │ Scores │ Votes ┤
╞══════╪═════════════════╪══════════════╪═════════╪════════╪═══════╡
│  0   │     FireFly     │      J       │   17    │  -15   │   6   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  1   │     tmartin     │     Kona     │   22    │  -10   │   2   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  2   │ Sven Hohenstein │      R       │   24    │   -8   │   7   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  3   │    Ben Reich    │  GolfScript  │   30    │   -2   │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  4   │    mollmerx     │      k       │   31    │   -1   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  5   │ David Carraher  │ Mathematica  │   31    │   -1   │   3   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  6   │     tmartin     │      Q       │   34    │   2    │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  7   │     daniero     │      dc      │   35    │   3    │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  8   │    psion5mx     │    Python    │   38    │   6    │   2   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  9   │       O-I       │     Ruby     │   39    │   7    │   5   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  10  │      gggg       │    Julia     │   40    │   8    │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  11  │ FakeRainBrigand │  LiveScript  │   50    │   18   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  12  │    Sylwester    │    Perl5     │   50    │   18   │   2   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  13  │     daniero     │     Ruby     │   55    │   23   │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  14  │    vasuakeel    │ Coffeescript │   57    │   25   │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  15  │      dirkk      │    XQuery    │   63    │   31   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  16  │  crazedgremlin  │   Haskell    │   64    │   32   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  17  │   Uri Agassi    │     Ruby     │   66    │   34   │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  18  │     Sumedh      │     JAVA     │   67    │   35   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  19  │      Danny      │  Javascript  │   67    │   35   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  20  │     deroby      │      c#      │   69    │   37   │   1   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  21  │  Adam Speight   │      VB      │   70    │   38   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  22  │    Andrakis     │    Erlang    │   82    │   50   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  23  │      Sp0T       │     PHP      │   85    │   53   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  24  │    brendanb     │   Clojure    │   87    │   55   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  25  │  Merin Nakarmi  │      C#      │   174   │  142   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  26  │    Boopathi     │     JAVA     │   517   │  485   │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  27  │      Noyo       │     ES6      │    ?    │   ?    │   2   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  28  │     shiona      │   Haskell    │    ?    │   ?    │   0   │
├──────┼─────────────────┼──────────────┼─────────┼────────┼───────┤
│  29  │      Vivek      │     int      │    ?    │   ?    │   0   │
└──────┴─────────────────┴──────────────┴─────────┴────────┴───────┘

Answer 1

J, 18 17 chars - 32 = ⁻15

[:+/&.:*:2&|+//.]

(As a "function body"; has to be parenthesized or bound to a name.)

Explanation

I tried making an exploded view of what each piece does, like Tobia does in APL answers.

               +//. ]    NB. sum up partitions
           2&|           NB.   given by equality on (x mod 2)
        *:               NB. square,
   +/                    NB. sum,
     &.:                 NB. then revert the squaring (square-root)
                         NB. (f&.:g in general acts like g⁻¹(f(g(x))))
[:                       NB. (syntax to indicate composition of +/&.:*: and (2&| +//. ]))

+/&.:*: could be replaced with |@j./ making use of O-I's complex magnitude trick to save yet another two characters.

Example

   f =: [:+/&.:*:2&|+//.]
   f 20 9 4 5 5 5 15 17 20 9
78.492

Answer 2

ES6, (48 - 32) = 16 (1 - 32) = -31

Original version:

f=l=>(e=o=0)+l.map(x=>x%2?e+=x:o+=x)&&Math.hypot(e,o)

Entire function definition is 53 characters, body only is 48.

Updated version, taking full advantage of the problem definition and moving pretty much everything out of the body and into the signature:

f=(l,e=0,o=0,g=x=>x%2?e+=x:o+=x,c=l.map(g)&&Math.hypot(e,o))=>c

New function definition is now 63 "punches" total, but function BODY is now just ONE DAMN CHARACTER LONG. Plus it no longer corrupts the global namespace! :D

Usage:

>>> f([20, 9, 4, 5, 5, 5, 15, 17, 20, 9])
78.49203781276161

Answer 3

R, (24 − 32) = −8

f=function(x)
    sum(by(x,x%%2,sum)^2)^.5  

The function body consists of 24 characters.

Usage:

f(c(20, 9, 4, 5, 5, 5, 15, 17, 20, 9))
[1] 78.49204

Answer 4

Ruby 2.1+ — (39 characters total - 7 non-body - 32 offset = 0)

Slightly different approach. I create a complex number a+b*i such that a and b are the sums of the even and odd numbers in list, respectively. Then I just take the absolute value.

f=->l{l.reduce{|s,x|s+x*1i**(x%2)}.abs}

My previous solution, which is 5 characters longer but works on 1.9.3+:

f=->l{l.reduce{|s,x|s+x*?i.to_c**(x%2)}.abs}

On a final note, if Rails + Ruby 2.1+ were allowed, we can use Array#sum to get the body down to a mere 25 characters:

l.sum{|x|x+1i**(x%2)}.abs

Answer 5

Python 2.7: 45, nay: 40, nay: 38 - 32 = 6

Nothing very new here, just a combination of the complex number trick I saw in the recent Pythagoras challenge, lambda for compactness, and syntax/parenthesis minimisation:

lambda x:abs(sum(a*(1-a%2+a%2*1j)for a in x))

Update - saved a few chars. Thanks to @DSM for the trick of raising the complex component to 0/1.

lambda x:abs(sum(a*1j**(a%2)for a in x))

Ok, reading the question and recognising the 'body of the function' count rule saves another 2 chars:

def f(x):
    return abs(sum(a*1j**(a%2)for a in x))

iPython testing:

In [650]: x = [20, 9, 4, 5, 5, 5, 15, 17, 20, 9]

In [651]: print (lambda l:abs(sum(a*(1-a%2+a%2*1j)for a in l)))(x)
78.4920378128

...

In [31]: def f(x):
   ....:     return abs(sum(a*1j**(a%2)for a in x))
   ....:

In [32]: f(x)
Out[32]: 78.49203781276162

Answer 6

APL (27 - 46 = -19)

{.5*⍨+/2*⍨+⌿⍵×[1]z,⍪~z←2|⍵}

e.g.:

      {.5*⍨+/2*⍨+⌿⍵×[1]z,⍪~z←2|⍵} 20 9 4 5 5 5 15 17 20 9
78.49203781

Answer 7

Mathematica 31-32 = -1

√Tr[(Tr/@GatherBy[#,OddQ])²]//N &

GatherBy[#,OddQ] produces the even-packet, odd-packet lists.

The inner Trfinds the totals, both of which are squared and then summed (by the outer Tr).

N converts from an irrational number (the square root of an integer) to a decimal approximation.

Example

√Tr[(Tr/@GatherBy[#,OddQ])²]//N &[{9, 5, 5, 5, 15, 17, 9, 20, 4, 20}]

78.492

---

If f[n_]:= is not included in the count, an additional character can be saved.

    f[n_]:=
    √Tr[(Tr/@GatherBy[n,OddQ])²]//N 

Example

f[{9, 5, 5, 5, 15, 17, 9, 20, 4, 20}]

78.492

Answer 8

Perl5 : (50 - 32 = 18)

map{$0[$_&1]+=$_}@ARGV;print sqrt$0[0]**2+$0[1]**2

Answer 9

dc 3 (35 - 32)

Using arrays, as suggested by @Tomas. This saves some of characters because I can calculate the parity of each number and use it as an index, instead of tweaking the with parity as a method of branching and putting the right values in the right registers. Also it turns out that arrays will give you a 0 even if the array/index haven't been used, so you don't have to initialize anything.

[d2%dsP;S+lP:Sz0<L]dsLx0;S2^1;S2^+v

Assumes the numbers are already on the stack, and leaves the result as the only value left when it's done.

Test:

$ dc  
20 9 4 5 5 5 15 17 20 9  
[d2%dsP;S+lP:Sz0<L]dsLx0;S2^1;S2^+v 
p
78

dc 16 (48 - 32)

First version using registers o and e to store odd and even numbers.

0dsose[dd2%rd1+2%*lo+so*le+sez0<x]dsxxle2^lo2^+v

Answer 10

Kona, 22 - 32 = -10

{(+/(+/'x@=x!2)^2)^.5}

Answer 11

Prolog (73 - 32 = 41)

Here we count everything after ':-' as the function body.

f([],0,0,0).
f([H|T],O,E,X):-(1 is H mod 2,f(T,S,E,_),O is H+S,!;f(T,O,S,_),E is H+S),sqrt(O*O+E*E,X).

Call function like so:

f([20, 9, 4, 5, 5, 5, 15, 17, 20, 9],_,_,X).

Answer 12

Julia, 40-46=-6

Implementation

function f(l)
    a=sum(l);b=sum(l[l%2 .==1]);hypot(a-b,b)
end

Output

julia> f([20, 9, 4, 5, 5, 5, 15, 17, 20, 9])
78.49203781276161

Answer 13

Python, 9 (55 - 46)

lambda x:sum([sum([i*(d-i%2) for i in x])**2for d in(0,1)])**0.5

Using a lambda function saves some bytes on newlines, tabs and return.

Example:

x = [20, 9, 4, 5, 5, 5, 15, 17, 20, 9]
print (lambda x:sum([sum([i*(d-i%2) for i in x])**2for d in(0,1)])**0.5)(x)
78.4920378128

Answer 14

Ruby, 55 - 46 = 9

f=->a{h=[0,0];a.map{|v|h[v%2]+=v};e,o=h;(e*e+o*o)**0.5}

Test:

f[[20, 9, 4, 5, 5, 5, 15, 17, 20, 9]] => 78.49203781276162`

Answer 15

Q, 34 - 32 = 2

{sqrt sum{x*x}(+/')(.)x(=)x mod 2}

.

q){sqrt sum{x*x}(+/')(.)x(=)x mod 2} 20 9 4 5 5 5 15 17 20 9
78.492037812761623

Answer 16

Ruby (66 - 32 = 34)

f=->a{o,e=a.partition(&:odd?).map{|x|x.reduce(:+)**2};(e+o)**0.5}

test:

f.([20, 9, 4, 5, 5, 5, 15, 17, 20, 9])
=> 78.49203781276162 

Answer 17

Coffeescript, (57 - 32 =25)

Implementaion

f=(a)->r=[0,0];r[e%2]+=e for e in a;[e,o]=r;(e*e+o*o)**.5

Answer 18

GolfScript 30

.{2%},]{{+}*}/.@\-]{2?}/+2-1??

I don't think GolfScript has much of a chance on this one!

Answer 19

c#: 69-32=37

double t=l.Sum(),o=l.Sum(x=>x*(x%2)),e=t-o;return Math.Sqrt(o*o+e*e);

Full code:

class Program
{
    static void Main(string[] args)
    {
        int[] list = { 20, 9, 4, 5, 5, 5, 15, 17, 20, 9 };
        Console.WriteLine(F(list));
        Console.ReadKey();
    }

    static double F(int[] l)
    {
        double t = l.Sum(),  // total sum of all elements
               o = l.Sum(x => x * (x % 2)),  // total of odd elements, if even %2 will return zero
               e = t - o; // even = total - odd
        return Math.Sqrt(o * o + e * e);
    }        
}

PS: Just for fun, this works too, sadly it doesn't change the number of characters needed:

double t=l.Sum(),o=l.Sum(x=>x*(x%2));return Math.Sqrt(t*t-2*o*(t-o));

Answer 20

C# 174

using System;class P{static void Main(){double[] L={20,9,4,5,5,5,15,17,20,9};double O=0,E=0;foreach(int i in L){if(i%2==0)E+=i;else O+=i;}Console.Write(Math.Sqrt(E*E+O*O));}}

Readable

using System;
class P
{
  static void Main()
  {
      double[] L = { 20, 9, 4, 5, 5, 5, 15, 17, 20, 9 };
      double O = 0, E = 0;
      foreach (int i in L)
      {
        if (i % 2 == 0)
            E += i;
        else
            O += i;
      }
      Console.Write(Math.Sqrt(E * E + O * O));
   }
}

Answer 21

Matlab (44 - 46 = -2)

Function body is 44 characters:

C=mod(A,2)>0;O=(sum(A(C))^2+sum(A(~C))^2)^.5

Total function as follows:

function O = Q(A)
C=mod(A,2)>0;O=(sum(A(C))^2+sum(A(~C))^2)^.5
end

Tests of the function:

>> A = [20 9 4 5 5 5 15 17 20 9];
>> Q(A)

O =

   78.4920


ans =

   78.4920

---

>> B = [8 3 24 1 9 8 4 5 52];
>> Q(B)

O =

   97.6729


ans =

   97.6729

Answer 22

Python 2.7 - 64-46 = 18

This could be shorter using some zip magic, but for now:

(sum(s for s in x if s%2)**2+sum(s for s in x if s%2==0)**2)**.5

For completion, it turns out you can do zip magic, but it costs you more (by a few characters), so the above stands, unless someone can improve either of these:

sum(map(lambda i:sum(i)**2,zip(*[[(0,i),(i,0)][i%2]for i in x])))**.5

Answer 23

Clojure = 87 - 46 = 41

(defn cd [v]
  (let [a apply ** #(* % %)]
    (Math/sqrt(a + (map #(** (a + (% 1)))(group-by even? v))))))

Hardly idiomatic, though.

Answer 24

Haskell, 64C - 46 = 18

c x=sqrt$fromIntegral$s(f odd x)^2+s(f even x)^2
f=filter
s=sum

Not too difficult to read. Example run:

*Main> c [1..10]
39.05124837953327

Answer 25

PHP 85-32=53

$a=$b=0;foreach($x as $q){if(($q%2)==0)$a=$a+$q;else$b=$b+$q;}echo sqrt($a*$a+$b*$b);

This is the best i'ld come up being a newbie. I'm sure there must be some shorter versions as well.

EDIT:

A reduced version of the code could be:

foreach($x as$q)($q%2)?$a=$a+$q:$b=$b+$q;echo sqrt($a*$a+$b*$b);

This version only has 64 (21 less than the original answer) chars.

Said so, 64-32=32

Answer 26

int e=0,o=0;for(int i :n){if(i%2==0)e+=i;else o+=i;}System.out.println(Math.sqrt(e*e+o*o));

Actual method in java code

public static void checkDigit(int[] n)
{
    int e=0,o=0;for(int i :n){if(i%2==0)e+=i;else o+=i;}System.out.println(Math.sqrt(e*e+o*o));
}

Test Class

public class Sint
{
    public static void main(String[] args)
    {
        if(args == null || args.length == 0)
            args = "20 9 4 5 5 5 15 17 20 9".split(" ");
        int[] n = null;
        try
        {
            n = new int[args.length];
            for(int i=0; i<args.length; i++)
                n[i] = Integer.parseInt(args[i]);
            System.out.print("int array is: ");
            for(int dd : n) System.out.print(dd+", ");
            System.out.print("\n");
            checkDigit(n);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public static void checkDigit(int[] n)
    {
        int e=0,o=0;for(int i :n){if(i%2==0)e+=i;else o+=i;}System.out.println(Math.sqrt(e*e+o*o));
    }
}

Answer 27

Erlang: 82C - 32 = 50

fun(L)->F={lists,sum},O=[X||X<-L,X rem 2>0],E=F(L--O),math:sqrt(F(O)*F(O)+E*E)end.

Erlang isn't great for this. Most shortcuts end up being more characters (tuples etc.)

The only real things of note:

• {lists,sum} is a function reference to lists:sum and can be called
• Even numbers are calculated by subtracting -- (list subtract) the odd numbers list from the full list

Can call using:

fun(L)->F={lists,sum},O=[X||X<-L,X rem 2>0],E=F(L--O),math:sqrt(F(O)*F(O)+E*E)end([20,9,4,5,5,5,15,17,20,9]).

Output: 78.49203781276162

Answer 28

VB.net (81c - 11c = 70) - 32 = 38

Via liberal usage of the term Write a function

Function(n)Math.Sqrt(n.Sum(Function(x)x Mod 2=0)^2+n.Sum(Function(x)x Mod 2=1)^2)

Answer 29

XQuery, (63 - 32 = 31)

Implementation

declare default function namespace 'http://www.w3.org/2005/xpath-functions/math';
declare function local:f($s) {
  sqrt(pow(fn:sum($s[. mod 2=0]),2)+pow(fn:sum($s[. mod 2=1]),2))
};

Output

local:f((20, 9, 4, 5, 5, 5, 15, 17, 20, 9))

BaseX was used as XQuery processor.

Answer 30

Haskell

57 - 32 = 25

Straight optimization of crazedgremlins answer:

c x=sqrt$read$show$sum(odd%x)^2+sum(even%x)^2
(%)=filter

Optimizations:

• read$show is shorter than fromIntegral - 3 chars
• s=sum\n and two s's has total length of 8 chars, two sum's is just 6 chars. - 2 chars
• making filter into operator does away with need of whitespace - 2 chars

I also tried adding more stuff to the operator, but it ended up being just as long:

c x=sqrt$read$show$odd%x+even%x
(%)=(((^2).sum).).filter

Answer 31

Tcl, 60 bytes (bonuses not included yet)

proc C L {lmap c $L {incr [expr $c%2] $c}
expr hypot($0,$1)}

Try it online!

Answer 32

JAVA: 67-32=35

inside function(int[] a) :

int x=0,y=0;
for(int i:a)
{
if(i%2==0)
x+=i;
else y+=i;
}
Math.hypot(x,y);

Answer 33

JAVA 517 bytes

 public class Link 
    {
        public static void main(String[] args) 
        {
            int[]a={20, 9, 4, 5, 5, 5, 15, 17, 20, 9};
            int []b=new int[10];
            int[]c=new int[10];
            int j=0,k=0,l=0,m=0;
            for(int i=0;i<a.length;i++)
            {
                if(a[i]%2==0)
                {
                    b[j]=a[i];
                    j++;
                }
                else
                {
                    c[k]=a[i];
                    k++;
                }
            }
            for(int i=0;i<j;i++)
            {
                l=l+b[i];
            }
            l=l*l;
            for(int i=0;i<k;i++)
            {
                m=m+c[i];
            }
            m=m*m;
            l=l+m;
            double t=Math.sqrt(l);
            System.out.print(t);
        }

    }

Answer 34

Javascript 67-32=35

function r(a){k=j=0;a.map(function z(i){i%2?j+=i:k+=i});return Math.sqrt(k*k+j*j)}

Doesn't seem like there is an easy way of spliting the array into even's and odd's without defining another function :(

console.log(r([20, 9, 4, 5, 5, 5, 15, 17, 20, 9]));
78.49203781276162

Answer 35

LiveScript 50 (or 1 if you're flexible)

The 1 character solution is r where the function signature is this:

fun = (a,o=(sum a.filter odd),e=(sum a.filter even),r=(e*e+o*o)**0.5) ->

But I think that's a technicality.

Actual answer:

o=sum a.filter odd
e=sum a.filter even
(e*e+o*o)^0.5

Answer 36

k (31-32 = -1)

sqrt{+/b*b:+/'(.)x@=(_a)=a:x%2}

Example run:

  sqrt{+/b*b:+/'(.)x@=(_a)=a:x%2} 20 9 4 5 5 5 15 17 20 9
78.492037812761623

Answer 37

C (68-32 = 36)

float f(int *a, int c)
{int s[2]={0};while(c--)s[a[c]%2]+=a[c];return sqrt(*s**s+s[1]*s[1]);}

In action:

#include <stdio.h>
#include <math.h>

float f(int *a, int c)
{int s[2]={0};while(c--)s[a[c]%2]+=a[c];return sqrt(*s**s+s[1]*s[1]);}

int main(void)
{
    printf("%f\n", f((int[]){20, 9, 4, 5, 5, 5, 15, 17, 20, 9}, 10));
    return 0;
}

Answer 38

ised (10 characters - 32) = -22

ASCII:

@={@+E$1@+O$1}

UTF8:

@={ΣE$1ΣO$1}

The variable $1 must contain the array. Example invocation from shell:

ised --l - '@={ΣE$1ΣO$1}' <<<"20, 9, 4, 5, 5, 5, 15, 17, 20, 9"

Example invocation in interactive mode:

ised> @1{20, 9, 4, 5, 5, 5, 15, 17, 20, 9}
20 9 4 5 5 5 15 17 20 9
ised> @={ΣE$1ΣO$1}
78.492

Explanation: operators O and E extract odd and even elements of the array. The operator @+ or Σ sums the array. @= returns the length of the given vector.

If you want a function, it's even shorter. Saving a function:

ised> @2{: @={ΣExΣOx} :}

The function body is only 10 characters long. The rest is the function declaration ({: :}) and storage of the function handle into memory slot 2 (@2). Invocation

ised> $2::{20 9 4 5 5 5 15 17 20 9}

Link to software: http://ised.sourceforge.net/