118 lines
2.1 KiB
Crystal
118 lines
2.1 KiB
Crystal
require "advent"
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input = input(2020, 23).lines[0].chars.map &.to_i32
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class Array(T)
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def get(i)
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self[i % size]
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end
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def del(i)
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delete_at(i % size)
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end
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end
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class Node
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property next : Node
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property int : Int32
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def initialize(@int, @next)
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end
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def insert(other : Node, n = 1)
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set_next = other
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(n-1).times { set_next = set_next.@next }
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set_next.next = @next
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@next = other
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end
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def remove(n = 1)
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curr = self
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to_return = self.next
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n.times { curr = curr.@next }
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@next = curr.@next
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to_return
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end
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def find(n)
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start = self
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while start.int != n
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start = start.next
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end
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return start
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end
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def to_s(n)
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return "" if n < 0
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return "#{@int} -> #{@next.to_s(n-1)}"
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end
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def includes?(n, count)
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return false if count <= 0
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return @int == n || @next.includes?(n, count-1)
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end
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end
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class Cups
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getter size : Int32
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getter head : Node
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def initialize(list : Array(Int32))
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@cache = {} of Int32 => Node
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h = list.delete_at(0)
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temp = uninitialized Node
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@cache[h] = @head = Node.new(h, temp)
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@size = list.size
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@local_min = list.min.as(Int32)
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@local_max = list.max.as(Int32)
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@head.next = @head
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curr = @head
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list.each do |n|
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@cache[n] = new = Node.new(n, curr.next)
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curr.insert(new)
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curr = new
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end
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end
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def to_s
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@head.to_s(@size)
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end
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def step
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first = @head
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after = first.remove(3)
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m = first.int - 1
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while after.includes?(m, 3) || m < @local_min
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m = (m < @local_min) ? @local_max : (m - 1)
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end
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@cache[m].insert(after, 3)
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@head = @head.next
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end
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end
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def play(input, count)
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cups = Cups.new input
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count.times { |n| cups.step }
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cups
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end
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def part1(input)
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cups = play(input.clone, 100)
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cups.head.find(1).next.to_s(cups.size - 1).gsub(" -> ", "")
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end
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def part2(input)
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list = input.clone
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max = input.max
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(1000000 - input.size).times do
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max += 1
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list << max
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end
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cups = play(list, 10000000)
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one = cups.head.find(1)
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one.next.int.to_i64 * one.next.next.int
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end
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puts "Part 1: #{part1(input)}"
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puts "Part 2: #{part2(input)}"
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