Compute odds of receiving N instances of symbol Y in a throw of M dice with SYMBOLS faces

throw.rb

# Compute odds of occurrence of N symbol Y in M dice
#

symbols = ARGV[0].split(",")   # ["s", "ss", "sss", "h", "b", "f"]
m = ARGV[1].to_i
n = ARGV[2].to_i
y = ARGV[3]

def to_radix(int, radix)
  int == 0 ? [] : (to_radix(int / radix, radix) + [int % radix])
end

z = symbols.size

# What are the chances of throwing 6 's' with three dice

counter = 0.0
total = comb = z ** m

puts "total combinations available is #{comb}"

while (comb >= 0) do
  t = to_radix(comb, z)
  if t.size < m
    t.insert(0, *Array.new(m - t.size, 0))
  end
  syms = t.collect { |sym_inx|
    symbols[sym_inx]
  }.join
  puts "#{comb}: #{syms}"

  # Increment counter if this 'roll' satisfies check
  if syms.count(y) >= n
    counter += 1.0
  end

  comb -= 1
end

puts "total throws #{total}"
puts "odds of there being #{n} occurrences of symbol #{y} in a throw of #{m} #{z}-sided dice = #{'%.2f' % (counter/total * 100.0)}%"