AdventOfCode-2020/day1.cr

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require "advent"
INPUT = input(2020, 1).lines.map(&.chomp.to_i32)
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def part1
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input = INPUT.clone.sort!
bottom = 0
top = input.size - 1
loop do
sum = input[bottom] + input[top]
if sum == 2020
puts input[bottom] * input[top]
return
elsif sum > 2020
top -= 1
else
bottom += 1
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end
end
end
def part2
input = INPUT.clone
input.each_with_index do |v, i|
input.each_with_index do |v2, j|
next if j == i
input.each_with_index do |v3, k|
next if k == j || k == i
puts v3*v2*v if v3 + v2 + v == 2020
end
end
end
end
part1
part2