From 3d5c13cf6af52da0e30481a4bfadc689151de69f Mon Sep 17 00:00:00 2001 From: Danila Fedorin Date: Fri, 4 Dec 2020 21:32:28 -0800 Subject: [PATCH] Add day 5 solution. --- day5.cr | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 day5.cr diff --git a/day5.cr b/day5.cr new file mode 100644 index 0000000..9c13978 --- /dev/null +++ b/day5.cr @@ -0,0 +1,55 @@ +INPUT = File.read("day5.txt").lines.map(&.chomp) + +def partition(choices, list) + b = 0 + e = list.size + choices.chars.each do |c| + b = (b+e)//2 if c == 'B' || c == 'R' + e = (b+e)//2 if c == 'F' || c == 'L' + end + + return {b,e} +end + +def get_id(str) + col = str[0..6] + row = str[7..] + {partition(col, (0..127).to_a)[0], partition(row, (0..7).to_a)[0]} +end + +def id(t) + r, c = t + r * 8 + c +end + +def part1 + input = INPUT.clone + max = input.max_of do |line| + r, c = get_id(line) + r * 8 + c + end + puts max +end + +def part2 + input = INPUT.clone + seen = Set(Int32).new + max = input.each do |line| + seen << id(get_id(line)) + end + candidates = [] of Int32 + 128.times do |r| + next if r == 0 || r == 127 + 8.times do |c| + next if seen.includes? id({r, c}) + candidates << id({r,c}) + end + end + candidates = candidates.select do |i| + seen.includes?(i-1) && seen.includes?(i+1) + end + puts candidates[0] +end + +part1 +part2