Create a World Cup guessing program

Question

As you know, the World Cup group stage is over, and from tomorrow the best 16 teams will commence the knockout stage:

• Brazil (BRA)
• Mexico (MEX)
• Netherlands (NED)
• Chile (CHI)
• Colombia (COL)
• Greece (GRE)
• Costa Rica (CRC)
• Uruguay (URU)
• France (FRA)
• Switzerland (SUI)
• Argentina (ARG)
• Nigeria (NGA)
• Germany (GER)
• United States (USA)
• Belgium (BEL)
• Algeria (ALG)

In the knockout stage, after each match the winner gets through to the next round, and the loser goes home (there are no draws). Click here to see more about the knockout stage.

You have been hired by golfbet.com, a new betting website because you are known to be good at both programming and sports betting. Your task is to write a program or function which can guess the winner of a match. Of course, everybody makes different guesses, it doesn't matter as long as your guesses are consistent.

If you don't want to guess, you can use the following guesses:

BRA
        BRA
CHI
                BRA
COL
        COL
URU
                        GER
FRA
        FRA
NGA
                GER
GER
        GER
ALG
                                        GER
NED
        NED
MEX
                NED
CRC
        CRC
GRE
                        ARG
ARG
        ARG
SUI
                ARG
BEL
        BEL
USA

1. The program has to output the same winner regardless the order of the to teams (the winner of the BRA-CHI match has to be the same as of the CHI-BRA match)
2. If a team loses, it cannot play any more matches. This means for matches that don't take place, you have to indicate so. For example if your program guesses Brazil to win the BRA-CHI match, then CHI-GER has to return "no result", because Chile won't play against Germany. See the link above for schedule.

For the sake of simplicity you don't have to deal with the bronze match (but you can of course).

Your program or function takes two strings as input: the 3-letter country code of the two teams and returns the country code of the winning team (you can use standard input/output, or two function parameters/return value). If the given two teams will not play according to your guesses, you must return something else (this can be anything but the country codes, eg empty string, null, error message). You can assume the input is correct (two different country codes which are in the list).

This is primarily a code-golf, so shortest program in bytes wins. However, nice and tricky solutions are also valuable.

Example (of course, you can make your own guesses):

input: BRA CHI output: BRA

input: CHI BRA output: BRA

input: CHI GER output: no result

Answer 1

Python 2.x - 368 283

Interesting challenge. Of course we need to get present rankings from the FIFA. Brazil have the so-called "12th man" as they have home advantage therefore the weighting 12/11.

a='BRA CHI COL URU FRA NGA ALG GER MEX NED CRC GRE ARG SUI BEL USA'.split()
d=[1242*12/11,1026,1137,1147,913,640,858,1300,882,981,762,1064,1175,1149,1074,1035]
m={}
for n in[16,8,4,2]:
 j=0
 for k in range(0,n,2):
  s=a[k] if d[k]>d[k+1] else a[k+1]
  m[a[k]+' '+a[k+1]]=s
  a[j]=s    
  j+=1
def f(s): 
 try: print m[s] 
 except: print 'no result'   

Tips to shorten the above are welcome :-).

Improvements thanks to @TheRare and @MrLemon

a='BRA CHI COL URU FRA NGA ALG GER MEX NED CRC GRE ARG SUI BEL USA'.split()
d=15,6,10,11,4,0,2,14,3,5,1,8,13,12,9,7
m={}
for n in 16,8,4,2:
 j=0
 for k in range(0,n,2):s=a[k]if d[k]>d[k+1]else a[k+1];m[a[k]+' '+a[k+1]]=s;a[j]=s;j+=1     
def f(s):print s in m and m[s]or'no result'

This leads to the following results:

BRA CHI: BRA
COL URU: URU
FRA NGA: FRA
ALG GER: GER
MEX NED: NED
CRC GRE: GRE
ARG SUI: ARG
BEL USA: BEL
------------
BRA URU: BRA
FRA GER: GER
NED GRE: GRE
ARG BEL: ARG
------------
BRA GER: BRA
GRE ARG: ARG
------------
BRA ARG: BRA

Example calls:

f('BRA MEX')
no result
f('BRA CHI')
BRA

Answer 2

C, 182 178 133 (or 126)

Not the shortest program here, but it is the shortest in which the prediction can be changed easily. Now that all the semifinalists are known, I'm updating.

There's some changes to the code, too. Apart from Dennis's suggestions in the comments, the program has been converted to a function (as on re-reading this is allowed by the rules) and the hashing has been shortened.

Code,133

f(char*a,char*b){
  char*p,*t=" HIAEAIH N?=R=?N ;@4S4@; 5BDGDB5 B@?I?@B",h[3]={*a-a[1]%16,*b-b[1]%16};
  (p=strstr(t,h))&&puts(p-t&2?a:b);
}

How it works

the inputs a and b are hashed by the expression *a-a[1]%16 to a single character (*a is a shorter equivalent to a[0]). The hash results for teams a and b are stored in h. For example BRA CHI becomes @;. Hashed values are as follows (the confirmed semifinalists and my predicted champion are marked with *.)

GRE E   CRC A   *NED I   MEX H
USA R   BEL =   *ARG ?   SUI N
URU S   COL 4  **BRA @   CHI ;
NGA G   FRA D   *GER B   ALG 5

t[] stores my predictions. The results of the round of 16 and quarter finals are now known. Each group of 4 teams is ordered such that the 1st and 4th were eliminated, and the 3rd is the semifinalist. Similarly of the semifinalists, I'm predicting that the 1st and 4th will be eliminated and the 3rd semifinalist will be the overall winner. If you disagree with my predictions, simply reorder the table.

The predictions are stored in palindromic blocks to accommodate the possibility of the user entering the teams in either possible order. The ordering puts the winning teams of each set of 4 together to play a third match. Thus in the first group GREE lost to CRC and MEXH lost to NED. This sets up CRCA to play NEDI in the quarter final without having to repeat the typing. The string is padded with a space between each group of 4 teams / 7 characters to help ensure there is no output for teams that will not play each other.

The winner of each possible match in each group of 8 characters is as follows: invalid,b,a,a,b,b,a,invalid. Thus the correct choice of winner can be made by taking the position of h in t AND 2. Unfortunately the strstr function is not the most straighforward as it returns a pointer p, so we must subtract p from t to get the actual position in t. If the match is invalid (cannot be found in t), p is zero and the phrase no result is printed.

Some dubious improvements, 126

2 characters saved by an improved hash expression. Unfortunately, this requires the case of the teams to be as shown in the test program below the function (eg Bra instead of BRA as used in the program above.) I've satisfied myself that there is no way of doing this with a single operator, so 2 operators and a single-character constant is as good as it gets. Note also that Uru maps to space so an alternate character | is needed to separate the groups of teamcodes.

5 characters saved by eliminating t and treating the prediction string as a literal. This means it is impossible to know the address where the string is stored. However, provided it is not stored at zero, we are only interested in p&2 so the code will work if the address is divisible by 4. (Note that it is not allowed to treat pointer p directly as an integer, it must be subtracted from another pointer. I use the pointer a so a must also be divisible by 4.) One can be fairly confident on a 32 or 64 bit compiler/architecture strings will be stored in this way. This has been working fine for me on GCC/cygwin, though it refuses to compile on visual studio / windows.

g(char*a,char*b){
  char*p,h[3]={*a^a[1]+3,*b^b[1]+3};
  (p=strstr("|%&626&%|+4*#*4+|(71 17(|./3$3/.|/74&47/",h))&&puts(p-a&2?a:b);
}

main(){
  char team[16][4]={"Gre","Crc","Ned","Mex", "Usa","Bel","Arg","Sui", "Uru","Col","Bra","Chi", "Nga","Fra","Ger","Alg"}; 
  int i;
  for(i=1;i<16;i++){printf("%s %s \n",team[i-1],team[i]);g(team[i],team[i-1]);g(team[i-1],team[i]);}  
}

Answer 3

JavaScript 215 206 120 116

A lot of room for improvement:

ES5 - 215

a=prompt().split(' ');("BRACHI0COLURU0FRANGA0GERALG0NEDMEX0CRCGRE0ARGSUI0BELUSA0BRACOL0FRAGER0NEDCRC0ARGBEL0BRAGER0NEDARG0BRANED".split(0).filter(function(x){return x.match(a[0])&&x.match(a[1])})[0]||"").substr(0,3)

ES6 - 206

a=prompt().split(' ');("BRACHI0COLURU0FRANGA0GERALG0NEDMEX0CRCGRE0ARGSUI0BELUSA0BRACOL0FRAGER0NEDCRC0ARGBEL0BRAGER0NEDARG0BRANED".split(0).filter((x)=>{return x.match(a[0])&&x.match(a[1])})[0]||"").substr(0,3)

Regex Approach - 116

Thanks to ɐɔıʇǝɥʇuʎs for posting this link, it helped me making the regex

a=prompt().split(' ').sort();a.join('').match(/LG(.R(A|G)|GE)|RG(S|BE|CR)|ELUS|AC(H|O)|OLUR|CGR|CM|FRANG|XNE/)&&a[0]

Answer 4

Python (179 148 139 c.q. way too long)

f=lambda *l:sorted(l)[0]if"".join(sorted(l))in"BRACHI COLURU FRANGA ALGGER MEXNED CRCGRE ARGSUI BELUSA BRACOL ALGFRA CRCMEX ARGBEL BRAFRA CRCMEX ARGBEL BRAFRA ARGCRC ARGBRA"else 0

Everybody knows the country with the name that comes first in the alphabet is going to win. (This answer just exists to get things started)

Thanks to the charity of the guy(s) over here, I could shorten my answer by a bit:

import re;f=lambda *l:sorted(l)[0]if re.match('RGB|CM|RGS|CGR|L.F|XNE|EL.S|O.UR|RGCR|B.AF|L.GE|^BRACHI$|^FRANGA$|^BRACOL$',"".join(sorted(l)))else 0

This does assume valid teams, but doesn't need a valid line-up (f('BRA','NED') would return 0 (invalid match), but f('XNE') would return 'XNE'. I don't get from your question that this is a problem though. Feel free to re-abuse this regex as you see fit.

Thanks @Ventero, I know nothing about regexes.

import re;f=lambda*l:sorted(l)[0]if re.match('RGB|CM|RGS|CGR|L.F|XNE|EL.S|O.UR|RGCR|B.AF|L.GE|BRACHI|FRANGA|BRACOL',"".join(sorted(l)))else 0

Answer 5

Scala (150)

type s=String;var m=Map[s,s]();def f(x:(s,s))={var a=x._1;var b=x._2;if(b<a){b=a;a=x._1};if(m.getOrElse(a,a)=="")m.getOrElse(b,b)else{m=m+(b->"");a}}

Here are matches between "foo" and "bar" possible, also teams wich won't play in real against each other in the first rounds will have a result.(for example starting with BRA,ARG)

It's just recording loosing teams.

type s=String //just aliasing for saving characters
var m=Map[s,s]() //map for storing loosing teams, a set would do too
def f(x:(s,s))={
  var a=x._1 var b=x._2
  if(b<a){b=a;a=x._1};//swap if b<a lexographically
  if(m.getOrElse(a,a)=="")//if a has loosed previously
     m.getOrElse(b,b)// return b if b was not in the map else return ""
  else{
    m=m+(b->"") //add b to the map, because a will definitly win this amazing match
    a //and return a
  }
}

Called with:

f(("GER","BRA"))

Answer 6

PowerShell (261 221)

$a=Read-Host;$b=Read-Host;$x="CHIBRA","URUCOL","FRANGA","ALGGER","MEXNED","CRCGRE","SUIARG","BELUSA";0..($x.Length-2)|%{$x+=$x[2*$_].Substring(3)+$x[2*$_+1].Substring(3)};$x|?{"$a$b","$b$a"-eq$_}|%{$_.Substring(3);exit};0

As a relatively new PowerShell user, I find the pipeline absolutely amazing. I think next up might be to try and fiddle with the array to hopefully eliminate all these substring calls. (I had to add a call at the end or else it outputted both teams)

New member, first attempt at code golf!

Could have hard-coded the quarterfinal, semis, and finals to save a few characters, but >that wouldn't be quite as fun.

Should be simple enough to decipher, but it fulfills both conditions: gives same winner >regardless of order entered, and only returns a winner for matches that actually take >place!

Any advice for improvement would be greatly appreciated, thanks!

Original

$a=Read-Host;$b=Read-Host;$x=("CHIBRA","URUCOL","FRANGA","ALGGER","MEXNED","CRCGRE","SUIARG","BELUSA");for($c=0;$c-lt$x.length-1;$c+=2){$x+=$x[$c].Substring(3)+$x[$c+1].Substring(3)}foreach($i in $x){if($i-match$a-and$i-match$b){return $i.Substring(3)}}return 0

Answer 7

CJam, 64 58 bytes

lS/$_0=\:+4b256b1>:ca"oM-YtM-mM-^@}gM-^VM-^U8tM-=nM-^MfM-]oM-xgM-)tM-|m@gim{g_"2/&,*

The above uses caret and M- notation, since the code contains unprintable characters.

At the cost of six additional bytes, those characters can be avoided:

lS/$_0=\:+4b95b1>32f+:c"I8Vyv)2~N{VIEh1$IW32W)B82QBs2G"2/N*\#W>*

Try it online.

Test run

$ base64 -d > worldcup.cjam <<< \
> bFMvJF8wPVw6KzRiMjU2YjE+OmNhIm/ZdO2AfWeWlTh0vW6NZt1v+GepdPxtQGdpbXtnXyIyLyYsKg==
$ wc -c worldcup.cjam
58 worldcup.cjam
$ for A in ALG ARG BEL BRA CHI COL CRC FRA GER GRE MEX NED NGA SUI URU USA; do
> for B in ALG ARG BEL BRA CHI COL CRC FRA GER GRE MEX NED NGA SUI URU USA; do
> [[ $A < $B ]] && echo $A - $B : $(LANG=en_US cjam worldcup.cjam <<< "$A $B")
> done; done | grep ': .'
ALG - ARG : ALG
ALG - BRA : ALG
ALG - FRA : ALG
ALG - GER : ALG
ARG - BEL : ARG
ARG - CRC : ARG
ARG - SUI : ARG
BEL - USA : BEL
BRA - CHI : BRA
BRA - COL : BRA
COL - URU : COL
CRC - GRE : CRC
CRC - MEX : CRC
FRA - NGA : FRA
MEX - NED : MEX

How it works

lS/$    " Read one line from STDIN, split at spaces and sort the resulting array.         ";
_0=\    " Extract the first element of a copy of the array and swap it with the array.    ";
:+      " Concatenate the strings.                                                        ";
4b      " Convert the resulting string into an integer by considering it a base 4 number. ";
256b    " Convert the integer into an array by considering it a base 256 number.          ";
1>:ca   " Drop the first element, convert into a string and create a singleton array.     ";
"…"     " Push a string of all matches encoded as explained above.                        ";
2/      " Split the string into an array of two-character strings.                        ";
&       " Intersect the two arrays. If the array is non-empty, the teams play.            ";
,*      " Multiply the string on the stack by the length of the array.                    ";

Answer 8

CJam, 49 48 bytes

lS/$_0="^\16@&^^/+(^]^W^Y,>O?"{_2%+}3*@{2b91%c}%#1&!*

The above uses caret notation, since the code contains unprintable characters.

At the cost of two additional bytes, those characters can be avoided:

lS/$_0="(=BL2*;74)#%8J[K"{_2%+}3*@{2b91%C+c}%#1&!*

Try it online.

Test run

$ base64 -d > wc.cjam <<< bFMvJF8wPSIcMTZAJh4vKygdFxksPk8/IntfMiUrfTMqQHsyYjkxJWN9JSMxJiEq
$ wc -c wc.cjam
48 wc.cjam
$ for A in ALG ARG BEL BRA CHI COL CRC FRA GER GRE MEX NED NGA SUI URU USA; do
> for B in ALG ARG BEL BRA CHI COL CRC FRA GER GRE MEX NED NGA SUI URU USA; do
> [[ $A < $B ]] && echo $A - $B : $(cjam wc.cjam <<< "$A $B"); done; done | grep ': .'
ALG - ARG : ALG
ALG - BRA : ALG
ALG - FRA : ALG
ALG - GER : ALG
ARG - BEL : ARG
ARG - CRC : ARG
ARG - SUI : ARG
BEL - USA : BEL
BRA - CHI : BRA
BRA - COL : BRA
COL - URU : COL
CRC - GRE : CRC
CRC - MEX : CRC
FRA - NGA : FRA
MEX - NED : MEX

Background

We start by assigning and ASCII character to each team by considering its name a base 2 number, taking the resulting integer modulo 91, adding 12 (to avoid unprintable characters) and selecting the character corresponding to the resulting ASCII code. In CJam code, this is achieved by 2b91%c.

For example, the character codes of ALG are 65 76 71. Since (4 × 65 + 2 × 76 + 71) = 483, 483 % 91 + 12 = 40 and 40 if the character code of (.

This gives the following mapping:

ALG (    ARG 4    BEL #    BRA 2    CHI *    COL ;    CRC 8    FRA B
GER =    GRE J    MEX [    NED K    NGA L    SUI )    URU 7    USA %

Now, we can encode the matches of the round of 16 as follows:

(=BL2*;74)#%8J[K

If we assume that the first team in alphabetical order always wins, the matches of the quarter-finals are as follows:

(B2;4#8[

Note that this string can be obtained from the first by selecting every second character, starting with the first. In CJam code, this is achieved by 2%.

Using the same idea, the matches of the semi-finals and the final match are as follows:

(248
(4

The code

"(=BL2*;74)#%8J[K"{_2%+}3*

pushes the string containing the matches of the round of 16, then does the following thrice: duplicate the string, extract every second character of the copy, concatenate. The result is the string

(=BL2*;74)#%8J[K(B2;4#8[(B2;4#8[(248(B2;4#8[(248(248(4

which contains all matches (some of them more than once).

How it works

lS/$        " Read one line from STDIN, split at spaces and sort the resulting array.     ";
_0=         " Extract the first element of a copy of the array.                           ";
"…"         " Push the string containing the matches of the round of 16.                  ";
{_2%+}3*    " Push the remaining matches.                                                 ";
@           " Rotate the input array on top of the stack.                                 ";
{2b91%C+c}% " Perform the mapping for each team in the input array.                       ";
#           " Push the index of the match in the array of all matches (-1 for not found). ";
1&!         " Push 1 if the index is even (valid match) and 0 if it is odd.               ";
,*          " Repeat the string on the stack that many times.                             ";

Answer 9

JavaScript 271

t=prompt('Match?').split('-')
x=t[0],y=t[1],T='BRACHICOLURUFRANGAGERALGNEDMEXCRCGREARGSUIBELUSA'
v='\n',R='',W='No Game'
for(z=1;T!='USA';++z,T=n){R+=v+z+v,n='',r=/(...)(...)/g
while(m=r.exec(T))a=m[1],n+=b=m[2],R+=a+'-'+b+v,W=a==x&&b==y||a==y&&b==x?b:W
}
alert(W+'\n'+R)