#!/usr/bin/lua
-- See https://adventofcode.com/2025/day/3

local DEBUG = false

function debug(msg)
	if DEBUG then
		print(msg)
	end
end

function MaxJolt(Battery, Size)
	debug("Staring Battery Check [" .. Battery .. "] Size [" .. Size .. "]")

	-- Load Battery into Array
	local BatteryTable = {}
	local BatterySize = string.len(Battery)
	for Cell in Battery:gmatch(".") do
		table.insert(BatteryTable, tonumber(Cell))
	end

	local Digits = {}
	local Start = 1

	-- Outer loop for Digits
	for I = 1, tonumber(Size) do
		debug("Checking digits " .. Start .. " till " .. (BatterySize - (Size - I)))
		Digits[I] = 0
		for Check = Start, BatterySize - (Size - I) do
			if Digits[I] < BatteryTable[Check] then
				Digits[I] = BatteryTable[Check]
				Start = Check + 1
			end
		end
	end

	return table.concat(Digits)
end

function TestMaxJolt(Battery, Test, Size)
	local MJ = MaxJolt(Battery, Size)
	if MJ == Test then
		print("WIN  - " .. Battery .. " " .. MJ .. " == " .. Test)
	else
		print("FAIL - " .. Battery .. " " .. MJ .. " != " .. Test)
	end
end

print("# Self Test")
TestMaxJolt("987654321111111", "987654321111", 12)
TestMaxJolt("811111111111119", "811111111119", 12)
TestMaxJolt("234234234234278", "434234234278", 12)
TestMaxJolt("818181911112111", "888911112111", 12)
--
print("# Calculate MaxJolt")
local TotalJolt = 0
--
for battery_line in io.lines("full_input") do
	local Jolt = MaxJolt(battery_line, 12)
	print(Jolt)
	TotalJolt = TotalJolt + Jolt
end
print("Total " .. string.format("%18.0f", TotalJolt))