Created
December 3, 2021 05:27
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def tally(data, ii) | |
Hash.new(0).tap do |h| | |
data.each { h[_1[ii]] += 1 } | |
end | |
end | |
n = data.first.length | |
# part 1 | |
gamma = (0...n).map do |ii| | |
tally = tally(data, ii) | |
tally['0'] > tally['1'] ? 0 : 1 | |
end | |
gamma = gamma.join.to_i(2) | |
epsilon = gamma ^ ((1 << n) - 1) | |
p gamma * epsilon | |
# part 2 | |
oxy, co2 = data.dup, data.dup | |
(0...n).each do |ii| | |
if oxy.length > 1 | |
tally = tally(oxy, ii) | |
keep = tally['0'] > tally['1'] ? '0' : '1' | |
oxy.select! { _1[ii] == keep } | |
end | |
if co2.length > 1 | |
tally = tally(co2, ii) | |
keep = tally['0'] > tally['1'] ? '1' : '0' | |
co2.select! { _1[ii] == keep } | |
end | |
end | |
oxy, co2 = oxy.first.to_i(2), co2.first.to_i(2) | |
p oxy * co2 |
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