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#!/usr/bin/ruby
#
# See ../README.md
#
#
# Run as: ruby ch-1.rb < input-file
#
def make_sequence (string, start)
if string == start
then return [start]
end
if 0 == string . index(start)
then tail = string [start . length, string . length]
result = make_sequence(tail, (start . to_i + 1) . to_s) ||
make_sequence(tail, (start . to_i - 1) . to_s)
if result
then return result . unshift (start)
end
end
return nil
end
ARGF . each_line do
|line|
line . strip!
for i in 1 .. line . length do
start = line [0, i]
result = make_sequence(line, start)
if result
then puts (result . join (","))
break
end
end
end
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