From b2f13520abd3be86cd677630d85aa37effe7fc1d Mon Sep 17 00:00:00 2001
From: Bill Rossi <bassguitarbill@gmail.com>
Date: Wed, 3 Dec 2025 05:59:18 -0500
Subject: [PATCH] 2025 ruby day 3, MAXIMUM_JOLTAGE

---
 ruby/2025/3/bin/problem                |  7 +++++++
 ruby/2025/3/lib/battery_bank.rb        | 27 ++++++++++++++++++++++++++
 ruby/2025/3/test/test_battery_banks.rb | 18 +++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 ruby/2025/3/bin/problem
 create mode 100644 ruby/2025/3/lib/battery_bank.rb
 create mode 100644 ruby/2025/3/test/test_battery_banks.rb

diff --git a/ruby/2025/3/bin/problem b/ruby/2025/3/bin/problem
new file mode 100644
index 0000000..0364648
--- /dev/null
+++ b/ruby/2025/3/bin/problem
@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+
+require "battery_bank"
+
+battery_banks = STDIN.read.chomp.split.map { |line| BatteryBank.for line }
+puts "Part 1: #{battery_banks.map(&:maximum_joltage).sum}"
+puts "Part 2: #{battery_banks.map(&:override_joltage).sum}"
\ No newline at end of file
diff --git a/ruby/2025/3/lib/battery_bank.rb b/ruby/2025/3/lib/battery_bank.rb
new file mode 100644
index 0000000..624d53e
--- /dev/null
+++ b/ruby/2025/3/lib/battery_bank.rb
@@ -0,0 +1,27 @@
+class BatteryBank
+  attr_reader :batteries
+
+  def initialize(batteries)
+    @batteries = batteries
+  end
+
+  def self.for(string)
+    new string.split("").map(&:to_i)
+  end
+
+  def joltage_for_batteries(num_batteries)
+    num_batteries.downto(1).reduce([[], 0]) do |acc, enabled_battery_index|
+      max_digit = batteries[(acc[1])..(-enabled_battery_index)].max
+      max_digit_index = batteries[(acc[1])..].find_index(max_digit)
+      [acc[0] + [max_digit], acc[1] + max_digit_index + 1]
+    end[0].map(&:to_s).join("").to_i
+  end
+
+  def maximum_joltage
+    joltage_for_batteries(2)
+  end
+
+  def override_joltage
+    joltage_for_batteries(12)
+  end
+end
diff --git a/ruby/2025/3/test/test_battery_banks.rb b/ruby/2025/3/test/test_battery_banks.rb
new file mode 100644
index 0000000..dc177f6
--- /dev/null
+++ b/ruby/2025/3/test/test_battery_banks.rb
@@ -0,0 +1,18 @@
+require "minitest/autorun"
+require "battery_bank"
+
+class TestBatteryBanks < ::Minitest::Test
+  def test_maximum_joltage
+    assert_equal(98, BatteryBank.for("987654321111111").maximum_joltage)
+    assert_equal(89, BatteryBank.for("811111111111119").maximum_joltage)
+    assert_equal(78, BatteryBank.for("234234234234278").maximum_joltage)
+    assert_equal(92, BatteryBank.for("818181911112111").maximum_joltage)
+  end
+
+  def test_override_joltage
+    assert_equal(987654321111, BatteryBank.for("987654321111111").override_joltage)
+    assert_equal(811111111119, BatteryBank.for("811111111111119").override_joltage)
+    assert_equal(434234234278, BatteryBank.for("234234234234278").override_joltage)
+    assert_equal(888911112111, BatteryBank.for("818181911112111").override_joltage)
+  end
+end