Sha256: 50f9c80e10943d97b3361d3c197458e11bff20ee6436f416f9bc5ec7cf44ee88
Contents?: true
Size: 534 Bytes
Versions: 6
Compression:
Stored size: 534 Bytes
Contents
class Integer
def delannoy?
return true if self == 1
max_a, max_b = self/2, self/2
(1..max_a).each do |a|
(1..max_b).each do |b|
d = a.delannoy(b)
return true if d == self
if d > self
max_b = b
max_a = a
break
end
end
break if a > max_a
end
false
end
def delannoy(b)
a = self
return 1 if b.zero? or a.zero?
[(a - 1).delannoy(b), a.delannoy(b - 1), (a - 1).delannoy(b - 1)].reduce(:+)
end
memoize :delannoy
end
Version data entries
6 entries across 6 versions & 1 rubygems