Sha256: b115be60b96d27e073f6b2fd52f51262e295058f775a456536a70ccacdf2b28e
Contents?: true
Size: 713 Bytes
Versions: 7
Compression:
Stored size: 713 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.
#
# [1,2].permutation(2).to_a #=> [[1,2], [2,1]]
#
# 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
7 entries across 6 versions & 1 rubygems