Rock, Paper, Scissors, Lizard, Spock [closed]

Question

Create a function that will take two strings as input and return a single output for the result. Most popular answer wins.

The rules of Rock-paper-scissors-lizard-Spock are:

• Scissors cut paper
• Paper covers rock
• Rock crushes lizard
• Lizard poisons Spock
• Spock smashes scissors
• Scissors decapitate lizard
• Lizard eats paper
• Paper disproves Spock
• Spock vaporizes rock
• Rock breaks scissors

The output for every possible input case is:

winner('Scissors', 'Paper') -> 'Scissors cut Paper'
winner('Scissors', 'Rock') -> 'Rock breaks Scissors'
winner('Scissors', 'Spock') -> 'Spock smashes Scissors'
winner('Scissors', 'Lizard') -> 'Scissors decapitate Lizard'
winner('Scissors', 'Scissors') -> 'Scissors tie Scissors'
winner('Paper', 'Rock') -> 'Paper covers Rock'
winner('Paper', 'Spock') -> 'Paper disproves Spock'
winner('Paper', 'Lizard') -> 'Lizard eats Paper'
winner('Paper', 'Scissors') -> 'Scissors cut Paper'
winner('Paper', 'Paper') -> 'Paper ties Paper'
winner('Rock', 'Spock') -> 'Spock vaporizes Rock'
winner('Rock', 'Lizard') -> 'Rock crushes Lizard'
winner('Rock', 'Scissors') -> 'Rock breaks Scissors'
winner('Rock', 'Paper') -> 'Paper covers Rock'
winner('Rock', 'Rock') -> 'Rock ties Rock'
winner('Lizard', 'Rock') -> 'Rock crushes Lizard'
winner('Lizard', 'Spock') -> 'Lizard poisons Spock'
winner('Lizard', 'Scissors') -> 'Scissors decapitate Lizard'
winner('Lizard', 'Paper') -> 'Lizard eats Paper'
winner('Lizard', 'Lizard') -> 'Lizard ties Lizard'
winner('Spock', 'Rock') -> 'Spock vaporizes Rock'
winner('Spock', 'Lizard') -> 'Lizard poisons Spock'
winner('Spock', 'Scissors') -> 'Spock smashes Scissors'
winner('Spock', 'Paper') -> 'Paper disproves Spock'
winner('Spock', 'Spock') -> 'Spock ties Spock'

Extra challenge suggested by @Sean Cheshire: Allow custom lists, such as those from this site. With the n-item list, the item loses to the (n-1)/2 previous, and wins over the (n-1)/2 following

Answer 1

APL

vs←{
    n←'Scissors' 'Paper' 'Rock' 'Lizard' 'Spock'
    x←n⍳⊂⍺ ⋄ y←n⍳⊂⍵ ⋄ X←⍺ ⋄ Y←⍵ ⋄ r←{X,⍵,⊂Y}
    x=y:     r (-x=0)↓'ties'
    y=5|1+x: r x⌷'cut' 'covers' 'crushes' 'poisons' 'smashes'
    y=5|3+x: r x⌷'decapitate' 'disproves' 'breaks' 'eats' 'vaporizes'
    ⍵∇⍺
}

Output exactly as required in all cases, including tie/ties. No lookup table, except for the actual words.

You can try it on http://ngn.github.io/apl/web/

'Spock' vs 'Paper'
Paper  disproves  Spock

APL just knows!

Answer 2

SED

#!/bin/sed
#expects input as 2 words, eg: scissors paper

s/^.*$/\L&/
s/$/;scissors cut paper covers rock crushes lizard poisons spock smashes scissors decapitates lizard eats paper disproves spock vaporizes rock breaks scissors/
t a
:a
s/^\(\w\+\)\s\+\(\w\+\);.*\1 \(\w\+\) \2.*$/\u\1 \3 \u\2/
s/^\(\w\+\)\s\+\(\w\+\);.*\2 \(\w\+\) \1.*$/\u\2 \3 \u\1/
t b
s/^\(\w\+\)\s\+\1;\(\1\?\(s\?\)\).*$/\u\1 tie\3 \u\1/
:b

Answer 3

Here is a general solution based on a rule string of any size. It performs correct capitalization for the proper name "Spock" and also allows rules for specifying 'tie' instead of 'ties' for plural objects.

def winner(p1, p2):
    rules = ('scissors cut paper covers rock crushes lizard poisons Spock'
    ' smashes scissors decapitate lizard eats paper disproves Spock vaporizes'
    ' rock breaks scissors tie scissors'.split())

    idxs = sorted(set(i for i, x in enumerate(rules) 
                      if x.lower() in (p1.lower(), p2.lower())))
    idx = [i for i, j in zip(idxs, idxs[1:]) if j-i == 2]
    s=' '.join(rules[idx[0]:idx[0]+3] if idx 
          else (rules[idxs[0]], 'ties', rules[idxs[0]]))
    return s[0].upper()+s[1:]

Results:

>>> winner('spock', 'paper')
'Paper disproves Spock'
>>> winner('spock', 'lizard')
'Lizard poisons Spock'
>>> winner('Paper', 'lizard')
'Lizard eats paper'
>>> winner('Paper', 'Paper')
'Paper ties paper'
>>> winner('scissors',  'scissors')
'Scissors tie scissors'    

Answer 4

Python

class Participant (object):
    def __str__(self): return str(type(self)).split(".")[-1].split("'")[0]
    def is_a(self, cls): return (type(self) is cls)
    def do(self, method, victim): return "%s %ss %s" % (self, method, victim)

class Rock (Participant):
        def fight(self, opponent):
                return (self.do("break", opponent)  if opponent.is_a(Scissors) else
                        self.do("crushe", opponent) if opponent.is_a(Lizard)   else
                        None)

class Paper (Participant):
        def fight(self, opponent):
                return (self.do("cover", opponent)    if opponent.is_a(Rock)  else
                        self.do("disprove", opponent) if opponent.is_a(Spock) else
                        None)

class Scissors (Participant):
        def fight(self, opponent):
                return (self.do("cut", opponent)       if opponent.is_a(Paper)  else
                        self.do("decaitate", opponent) if opponent.is_a(Lizard) else
                        None)

class Lizard (Participant):
        def fight(self, opponent):
                return (self.do("poison", opponent) if opponent.is_a(Spock) else
                        self.do("eat", opponent)    if opponent.is_a(Paper) else
                        None)

class Spock (Participant):
        def fight(self, opponent):
                return (self.do("vaporize", opponent) if opponent.is_a(Rock)     else
                        self.do("smashe", opponent)    if opponent.is_a(Scissors) else
                        None)

def winner(a, b):
    a,b = ( eval(x+"()") for x in (a,b))
    return a.fight(b) or b.fight(a) or a.do("tie", b)

Answer 5

Ruby, arithmetic approach

The actors can can be arranged in an array in such a way that each actor a[i] wins against the actors a[i+1] and a[i+2], modulo 5, for instance:

%w(Scissors Lizard Paper Spock Rock)

Then, for an actor A with index i we can see how he matches agains actor B with index j by doing result = (j-i)%5: Result 1 and 2 means that actor A won against an actor 1 or 2 places in front of him respectively; 3 and 4 similarly means he lost against an actor behind him in the array. 0 means a tie. (Note that this may be language dependent; in Ruby (j-i)%5 == (5+j-i)%5 also when j>i.)

The most interesting part of my code is the use of this property to find a sorting function of the indices of two actors. The return value will be -1, 0 or 1 as it should:

winner,loser = [i,j].sort { |x,y| ((y-x)%5+1)/2-1 }

Here's the whole thing:

def battle p1,p2
    who = %w(Scissors Lizard Paper Spock Rock)
    how = %w(cut decapitate poisons eats covers disproves smashes vaporizes crushes breaks)
    i,j = [p1,p2].map { |s| who.find_index s }

    winner,loser = [i,j].sort { |x,y| ((y-x)%5+1)/2-1 }

    method = (winner-loser)%5/2
    what = method == 0 && "ties" || how[winner*2 + method-1]

    return "#{who[winner]} #{what} #{who[loser]}"
end

Answer 6

Python

def winner(p1, p2):
    actors = ['Paper', 'Scissors', 'Spock', 'Lizard', 'Rock']
    verbs = {'RoLi':'crushes', 'RoSc':'breaks', 'LiSp':'poisons',
             'LiPa':'eats', 'SpSc':'smashes', 'SpRo':'vaporizes', 
             'ScPa':'cut', 'ScLi':'decapitate', 'PaRo':'covers', 
             'PaSp':'disproves', 'ScSc':'tie'}
    p1, p2 = actors.index(p1), actors.index(p2)
    winner, loser = ((p1, p2), (p2, p1))[(1,0,1,0,1)[p1 - p2]]
    return ' '.join([actors[winner],
                     verbs.get(actors[winner][0:2] + actors[loser][0:2],
                               'ties'),
                     actors[loser]])

Answer 7

Python

---

  def winner(p,q):
        if p==q:
           return(' '.join([p,'tie',q]))
        d = {'ca':'cut','ao':'covers','oi':'crushes','ip':'poisons','pc': 'smashes','ci':'decapitate','ia':'eats', 'ap':'disproves', 'po':'vaporizes','oc': 'breaks'}
        [a,b] = [p[1],q[1]]
        try:
           return(' '.join([p,d[a+b],q]))
        except KeyError:
           return(' '.join([q,d[b+a],p]))

Using a tricky dictionary.

Answer 8

C#

Assumptions

The opponents are arranged in an n-item array where players beat the (n-1)/2 players ahead of them and lose to the (n-1)/2 players behind them. (With even length lists, the player loses to the ((n-1)/2 + 1) players behind them)

Player actions are arranged in an array where actions within the range of [(indexOfPlayer * (n-1)/2)] to [(indexOfPlayer * (n-1)/2)) + (n-2)/2 - 1].

Additional Info

CircularBuffer<T> is a wrapper around an array to create an "infinitely" addressable array. The IndexOf function returns the index of an item within the actual bounds of the array.

The Class

public class RockPaperScissors<T> where T : IComparable
{
    private CircularBuffer<T> players;
    private CircularBuffer<T> actions;

    private RockPaperScissors() { }

    public RockPaperScissors(T[] opponents, T[] actions)
    {
        this.players = new CircularBuffer<T>(opponents);
        this.actions = new CircularBuffer<T>(actions);
    }

    public string Battle(T a, T b)
    {
        int indexA = players.IndexOf(a);
        int indexB = players.IndexOf(b);

        if (indexA == -1 || indexB == -1)
        {
            return "A dark rift opens in the side of the arena.\n" +
                   "Out of it begins to crawl a creature of such unimaginable\n" +
                   "horror, that the spectators very minds are rendered\n" +
                   "but a mass of gibbering, grey jelly. The horrific creature\n" +
                   "wins the match by virtue of rendering all possible opponents\n" +
                   "completely incapable of conscious thought.";
        }

        int range = (players.Length - 1) / 2;

        if (indexA == indexB)
        {
            return "'Tis a tie!";
        }
        else
        {
            indexB = indexB < indexA ? indexB + players.Length : indexB;
            if (indexA + range < indexB)
            {
                // A Lost
                indexB = indexB >= players.Length ? indexB - players.Length : indexB;
                int actionIndex = indexB * range + (indexA > indexB ? indexA - indexB : (indexA + players.Length) - indexB) - 1;

                return players[indexB] + " " + actions[actionIndex] + " " + players[indexA];
            }
            else
            {
                // A Won
                int actionIndex = indexA * range + (indexB - indexA) - 1;

                return players[indexA] + " " + actions[actionIndex] + " " + players[indexB];
            }
        }
    }
}

Example

string[] players = new string[] { "Scissors", "Lizard", "Paper", "Spock", "Rock" };
string[] actions = new string[] { "decapitates", "cuts", "eats", "poisons", "disproves", "covers", "vaporizes", "smashes", "breaks", "crushes" };

RockPaperScissors<string> rps = new RockPaperScissors<string>(players, actions);

foreach (string player1 in players)
{
    foreach (string player2 in players)
    {
        Console.WriteLine(rps.Battle(player1, player2));
    }
}
Console.ReadKey(true);

Answer 9

Python, one-liner

winner=lambda a,b:(
    [a+" ties "+b]+
    [x for x in 
        "Scissors cut Paper,Paper covers Rock,Rock crushes Lizard,Lizard poisons Spock,Spock smashes Scissors,Scissors decapitate Lizard,Lizard eats Paper,Paper disproves Spock,Spock vaporizes Rock,Rock break Scissors"
        .split(',') 
     if a in x and b in x])[a!=b]

Answer 10

Just a small thing I came up with:

echo "winners('Paper', 'Rock')"|sed -r ":a;s/[^ ]*'([[:alpha:]]+)'./\1/;ta;h;s/([[:alpha:]]+) ([[:alpha:]]+)/\2 \1/;G"|awk '{while(getline line<"rules"){split(line,a," ");if(match(a[1],$1)&&match(a[3],$2))print line};close("rules")}' IGNORECASE=1

Here, rules is the file containing all the rules that were given.

Answer 11

Python

Inspired by @Tobia's APL code.

def winner(p1, p2):
  x,y = map(lambda s:'  scparolisp'.find(s.lower())/2, (p1[:2], p2[:2]))
  v = (' cut covers crushes poisons smashes'.split(' ')[x*(y in (x+1, x-4))] or
       ' decapitate disproves breaks eats vaporizes'.split(' ')[x*(y in (x+3, x-2))])
  return ' '.join((p1.capitalize(), v or 'tie'+'s'*(x!=1), p2)) if v or p1==p2 \
    else winner(p2, p1)

Results:

>>> winner('Spock', 'paper')
'Paper disproves Spock'
>>> winner('Spock', 'lizard')
'Lizard poisons Spock'
>>> winner('paper', 'lizard')
'Lizard eats paper'
>>> winner('paper', 'paper')
'Paper ties paper'
>>> winner('scissors',  'scissors')
'Scissors tie scissors'    

Answer 12

C++

#include <stdio.h>
#include <string>
#include <map>
using namespace std ;
map<string,int> type = { {"Scissors",0},{"Paper",1},{"Rock",2},{"Lizard",3},{"Spock",4} };
map<pair<int,int>, string> joiner = {
  {{0,1}, " cuts "},{{0,3}, " decapitates "}, {{1,2}, " covers "},{{1,4}, " disproves "},
  {{2,3}, " crushes "},{{2,0}, " crushes "},  {{3,4}, " poisons "},{{3,1}, " eats "},
  {{4,0}, " smashes "},{{4,2}, " vaporizes "},
} ;
// return 0 if first loses, return 1 if 2nd wins
int winner( pair<int,int> p ) {
  return (p.first+1)%5!=p.second && (p.first+3)%5!=p.second ;
}
string winner( string sa, string sb ) {
  pair<int,int> pa = {type[sa],type[sb]};
  int w = winner( pa ) ;
  if( w )  swap(pa.first,pa.second), swap(sa,sb) ;
  return sa+(pa.first==pa.second?" Ties ":joiner[pa])+sb ;
}

A bit of a test

int main(int argc, const char * argv[])
{
  for( pair<const string&, int> a : type )
    for( pair<const string&, int> b : type )
      puts( winner( a.first, b.first ).c_str() ) ;
}

Answer 13

Javascript

function winner(c1,c2){
    var c = ["Scissors", "Paper", "Rock", "Lizard", "Spock"];
    var method={
        1:["cut", "covers", "crushes", "poisons", "smashes"],
        2:["decapitate", "disproves", "breaks", "eats", "vaporizes"]};
    //Initial hypothesis: first argument wins
    var win = [c.indexOf(c1),c.indexOf(c2)];
    //Check for equality
    var diff = win[0] - win[1];
    if(diff === 0){
        return c1 + ((win[0]===0)?" tie ":" ties ") + c2;
    }
    //If s is -1 we'll swap the order of win[] array
    var s = (diff>0)?1:-1;
    diff = Math.abs(diff);
    if(diff >2){
        diff = 5-diff;
        s= s * -1;
    }
    s=(diff==1)?s*-1:s;
    if(s === -1){
        win = [win[1],win[0]];
    }
    return c[win[0]] + " " + method[diff][win[0]] + " " + c[win[1]];
}

Answer 14

Javascript

I see this isn't a golfing contest, but I had been fiddling with this puzzle for a while before finding this thread, so here goes.

Here's a (standard) js version in 278 characters:

function winner(a,b){var c={rock:0,paper:1,scissors:2,spock:3,lizard:4},d="crushe,crushe,cover,disprove,cut,decapitate,smashe,vaporize,poison,eat".split(","),i=c[a],j=c[b],I=i==(j+3)%5;return i^j?i==(j+1)%5||I?a+" "+d[i*2+I]+"s "+b:b+" "+d[j*2+(j==(i+3)%5)]+"s "+a:a+" ties "+b}

Or one using E6 features (likely only works in Firefox) in 259 characters:

winner=(a,b,c={rock:0,paper:1,scissors:2,spock:3,lizard:4},d="crushe,crushe,cover,disprove,cut,decapitate,smashe,vaporize,poison,eat".split(","),i=c[a],j=c[b],I=i==(j+3)%5)=>i^j?i==(j+1)%5||I?a+" "+d[i*2+I]+"s "+b:b+" "+d[j*2+(j==(i+3)%5)]+"s "+a:a+" ties "+b