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# The MIT License
#
# All contents Copyright (c) 2004-2008 Reginald Braithwaite
# <http://braythwayt.com> except as otherwise noted.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# http://www.opensource.org/licenses/mit-license.php
module TemplateMethod
def divide_and_conquer(value)
if divisible?(value)
recombine(
divide(value).map { |sub_value| divide_and_conquer(sub_value) }
)
else
conquer(value)
end
end
private
def divisible?(value)
raise 'implement me'
end
def conquer(value)
raise 'implement me'
end
def divide(value)
raise 'implement me'
end
def recombine(list)
raise 'implement me'
end
end
include TemplateMethod
def divisible?(value)
value.kind_of?(Enumerable) && value.size > 1
end
def conquer(value)
value
end
def divide(square)
half_sz = square.size / 2
sub_square = lambda do |row, col|
square.slice(row, half_sz).map { |a_row|a_row.slice(col, half_sz) }
end
upper_left = sub_square.call(0,0)
lower_left = sub_square.call(half_sz,0)
upper_right = sub_square.call(0,half_sz)
lower_right = sub_square.call(half_sz,half_sz)
[upper_left, lower_left, upper_right, lower_right]
end
def recombine(list)
upper_left, lower_left, upper_right, lower_right = list
upper_right.zip(lower_right).map { |l,r| l + r } +
upper_left.zip(lower_left).map { |l,r| l + r }
end
p divide_and_conquer([[1,2,3,4], [5,6,7,8], [9,10,11,12], [13,14,15,16]])
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