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whatalnk/arc066-c.rb

Created March 10, 2017 07:29
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AtCoder ARC #066 / ABC #050 [Ruby]
Raw
arc066-c.rb
n = gets.chomp.to_i
a = gets.chomp.split(" ").map(&:to_i).sort
if n.even? then
ref = ((1..(n-1)).step(2).to_a * 2).sort
ans = 2**(n/2) % (10**9 + 7)
else
ref = ((2..(n-1)).step(2).to_a * 2 + [0]).sort
ans = 2**((n-1)/2) % (10**9 + 7)
end
if a == ref then
puts ans
else
puts 0
end
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