Sha256: bd5dd5a7995521cc3d35eddb9c24c21edd9551082bf3447d38b9f3b483e4dba3
Contents?: true
Size: 653 Bytes
Versions: 6
Compression:
Stored size: 653 Bytes
Contents
class Array
unless method_defined?(:permutation) # 1.8.7+
# Permutation provids the possible orders of an enumerable.
# Each is indexed by a permutation number. The maximum number of
# arrangements is the factorial of the size of the array.
#
# CREDIT: Shin-ichiro Hara
def permutation(n=size)
if size < n or n < 0
elsif n == 0
yield([])
else
self[1..-1].permutation(n - 1) do |x|
(0...n).each do |i|
yield(x[0...i] + [first] + x[i..-1])
end
end
self[1..-1].permutation(n) do |x|
yield(x)
end
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems