advent_of_code_day_22.rb

class Battle
  SPELLS = {
    "Magic Missile" => {cost: 53, damage: 4},
    "Drain" => {cost: 73, damage: 2, heal: 2},
    "Shield" => {cost: 113, timer: 6, effect: "armor", amount: 7},
    "Poison" => {cost: 173, timer: 6, effect: "poison", amount: 3},
    "Recharge" => {cost: 229, timer: 5, effect: "recharge", amount: 101},
  }

  def initialize
    @armor_effect_timer = 0
    @poison_effect_timer = 0
    @recharge_effect_timer = 0
    @enemy_hp = 51
    @enemy_dmg = 9
    @hp = 50
    @mana = 500
    @mana_use = 0
    @bad = false
  end

  def run
    until @hp <= 0 || @enemy_hp <= 0 do
      hero_turn
      break if @hp <= 0 || @enemy_hp <= 0
      enemy_turn
    end
    [@enemy_hp <= 0 && @bad == false, @mana_use]
  end

  def hero_turn
    @hp -= 1
    @bad = true if @hp <= 0
    status_effects
    this_spells = SPELLS
    this_spells.delete("Shield") if @armor_effect_timer != 0
    this_spells.delete("Poison") if @poison_effect_timer != 0
    this_spells.delete("Recharge") if @recharge_effect_timer != 0
    if @armor_effect_timer == 0 && (1..3).to_a.sample != 2
      spell, vars = ["Shield", {cost: 113, timer: 6, effect: "armor", amount: 7},]
    elsif @mana < 400 && @enemy_hp > 10 && (1..3).to_a.sample != 2
      spell, vars = ["Recharge", {cost: 229, timer: 5, effect: "recharge", amount: 101},]
    elsif @poison_effect_timer == 0 && (1..3).to_a.sample != 2
      spell, vars = ["Poison", {cost: 173, timer: 6, effect: "poison", amount: 3},]
    else
      spell, vars = this_spells.select do |k,v|
        v[:cost] < @mana
      end.to_a.sample
    end
    if spell == nil
      spell, vars = ["Recharge", {cost: 229, timer: 5, effect: "recharge", amount: 101},]
    end
    @mana -= vars[:cost]
    @bad = true if @mana < 0
    @mana_use += vars[:cost]
    @enemy_hp -= vars[:damage].to_i
    if vars[:timer]
      @armor_effect_timer += vars[:timer] if spell == "Shield"
      @poison_effect_timer += vars[:timer] if spell == "Poison"
      @recharge_effect_timer += vars[:timer] if spell == "Recharge"
    end
    if spell == "Drain"
      @hp += 2
    end
  end

  def enemy_turn
    status_effects
    if @armor_effect_timer > 0
      @hp -= (@enemy_dmg - 7)
    else
      @hp -= @enemy_dmg
    end
  end

  def status_effects
    if @armor_effect_timer > 0
      @armor_effect_timer -= 1
    end
    if @poison_effect_timer > 0
      @poison_effect_timer -= 1
      @enemy_hp -= 3
    end
    if @recharge_effect_timer > 0
      @recharge_effect_timer -= 1
      @mana += 101
    end
  end
end


20.times {
  these = 100000.times.map{ Battle.new.run }.select{|arr| arr[0] == true}
  p these.count
  answer = these.sort_by{|arr| arr[1]}
  p answer.first
}