wooo day7

day7.exs

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+defmodule DaySeven do
+  def part_one(input) do
+    deps = parse_input(input)
+    letters = Enum.map(?A..?Z, &(<<&1>>))
+    Enum.reverse resolve_instructions(deps, letters, [])
+  end
+
+  def part_two(input) do
+    deps = parse_input(input)
+    letters = Enum.map(?A..?Z, &(<<&1>>))
+    resolve_workers(deps, letters, [], 5, 0) - 1
+  end
+
+  def parse_input(input) do
+    regex = ~r/Step (\w) must be finished before step (\w) can begin\./
+    String.split(input, "\n") 
+      |> Enum.filter(&(&1 != "")) 
+      |> Enum.map(fn line -> 
+        [[_, on, dep]] = Regex.scan(regex, line)
+        {on, dep}
+    end)
+  end
+
+  def resolve_instructions([], [ letter ], acc), do: [letter | acc ]
+  def resolve_instructions(deps, remletters, acc) do
+    firsts = Enum.filter(remletters, fn letter -> not Enum.member?(Enum.map(deps, fn {_on, dep} -> dep end), letter) end)
+    [first | _ ] = firsts |> Enum.sort
+    rem = Enum.filter(deps, fn {on, _dep} -> on != first end)
+    rletters = Enum.filter(remletters, fn letter -> letter != first end)
+    resolve_instructions(rem, rletters, [first | acc])
+  end
+
+  def resolve_workers(_deps, [], _workers, _, acc), do: acc
+  def resolve_workers(deps, remletters, workers, maxworkers, acc) do
+    sworkers = Enum.map(workers, fn {task, time} -> {task, time - 1} end)
+    step_workers = Enum.filter(sworkers, fn {_, time} -> time != 0 end)
+    completed = Enum.filter(sworkers, fn {_, time} -> time == 0 end)
+                |> Enum.map(fn {task, _} -> task end)
+    uremletters = Enum.filter(remletters, &(not Enum.member?(completed, &1)))
+    udeps = Enum.filter(deps, fn {on, _dep} -> not Enum.member?(completed, on) end)
+    canwork = Enum.filter(uremletters, fn letter -> not Enum.member?(Enum.map(udeps, fn {_on, dep} -> dep end), letter) end) |> Enum.filter(fn letter -> not Enum.member?(Enum.map(step_workers, fn {task, _} -> task end), letter) end)
+    uworkers = if length(step_workers) < maxworkers and length(canwork) > 0 do
+      schedule_work(canwork, maxworkers - length(step_workers), step_workers)
+    else
+      step_workers
+    end
+
+    # IO.puts "Move #{acc}, now working on #{Enum.map(uworkers, fn {task, time} -> "(#{task}: #{time})" end) |> Enum.join(", ")}"
+    resolve_workers(udeps, uremletters, uworkers, maxworkers, acc + 1)
+  end
+
+  def schedule_work([], _, workers), do: workers
+  def schedule_work(_, 0, workers), do: workers
+  def schedule_work([work | tail], numworkers, workers) do
+    schedule_work(tail, numworkers - 1, [{work, time_taken(work)} | workers])
+  end
+
+  def time_taken(<< letter >>), do: letter - 4
+end
+
+{:ok, content} = File.read("input7.txt")
+
+IO.puts("Part 1: #{DaySeven.part_one(content)}")
+IO.puts("Part 2: #{DaySeven.part_two(content)}")

input7.txt

@@ -0,0 +1,101 @@
+Step X must be finished before step C can begin.
+Step C must be finished before step G can begin.
+Step F must be finished before step G can begin.
+Step U must be finished before step Y can begin.
+Step O must be finished before step S can begin.
+Step D must be finished before step N can begin.
+Step M must be finished before step H can begin.
+Step J must be finished before step Q can begin.
+Step G must be finished before step R can begin.
+Step I must be finished before step N can begin.
+Step R must be finished before step K can begin.
+Step A must be finished before step Z can begin.
+Step Y must be finished before step L can begin.
+Step H must be finished before step P can begin.
+Step K must be finished before step S can begin.
+Step Z must be finished before step P can begin.
+Step T must be finished before step S can begin.
+Step N must be finished before step P can begin.
+Step E must be finished before step S can begin.
+Step S must be finished before step W can begin.
+Step W must be finished before step V can begin.
+Step L must be finished before step V can begin.
+Step P must be finished before step B can begin.
+Step Q must be finished before step V can begin.
+Step B must be finished before step V can begin.
+Step P must be finished before step Q can begin.
+Step S must be finished before step V can begin.
+Step C must be finished before step Q can begin.
+Step I must be finished before step H can begin.
+Step A must be finished before step E can begin.
+Step H must be finished before step Q can begin.
+Step G must be finished before step V can begin.
+Step N must be finished before step L can begin.
+Step R must be finished before step Q can begin.
+Step W must be finished before step L can begin.
+Step X must be finished before step L can begin.
+Step X must be finished before step J can begin.
+Step W must be finished before step P can begin.
+Step U must be finished before step B can begin.
+Step P must be finished before step V can begin.
+Step O must be finished before step P can begin.
+Step W must be finished before step Q can begin.
+Step S must be finished before step Q can begin.
+Step U must be finished before step Z can begin.
+Step Z must be finished before step T can begin.
+Step M must be finished before step T can begin.
+Step A must be finished before step P can begin.
+Step Z must be finished before step B can begin.
+Step N must be finished before step S can begin.
+Step H must be finished before step N can begin.
+Step J must be finished before step E can begin.
+Step M must be finished before step J can begin.
+Step R must be finished before step A can begin.
+Step A must be finished before step Y can begin.
+Step F must be finished before step V can begin.
+Step L must be finished before step P can begin.
+Step K must be finished before step L can begin.
+Step F must be finished before step P can begin.
+Step G must be finished before step L can begin.
+Step I must be finished before step Q can begin.
+Step C must be finished before step L can begin.
+Step I must be finished before step Y can begin.
+Step G must be finished before step B can begin.
+Step H must be finished before step L can begin.
+Step X must be finished before step U can begin.
+Step I must be finished before step K can begin.
+Step R must be finished before step N can begin.
+Step I must be finished before step L can begin.
+Step M must be finished before step I can begin.
+Step K must be finished before step V can begin.
+Step G must be finished before step E can begin.
+Step F must be finished before step B can begin.
+Step O must be finished before step Y can begin.
+Step Y must be finished before step Q can begin.
+Step F must be finished before step K can begin.
+Step N must be finished before step W can begin.
+Step O must be finished before step R can begin.
+Step N must be finished before step E can begin.
+Step M must be finished before step V can begin.
+Step H must be finished before step T can begin.
+Step Y must be finished before step T can begin.
+Step F must be finished before step J can begin.
+Step F must be finished before step O can begin.
+Step W must be finished before step B can begin.
+Step T must be finished before step E can begin.
+Step T must be finished before step P can begin.
+Step F must be finished before step M can begin.
+Step U must be finished before step I can begin.
+Step H must be finished before step S can begin.
+Step S must be finished before step P can begin.
+Step T must be finished before step W can begin.
+Step A must be finished before step N can begin.
+Step O must be finished before step N can begin.
+Step L must be finished before step B can begin.
+Step U must be finished before step K can begin.
+Step Z must be finished before step W can begin.
+Step X must be finished before step D can begin.
+Step Z must be finished before step L can begin.
+Step I must be finished before step T can begin.
+Step O must be finished before step W can begin.
+Step I must be finished before step B can begin.