Almost there, commit before refactor

2025/Day3/Day3_first.lua

@@ -0,0 +1,56 @@
+#!/usr/bin/lua
+-- See https://adventofcode.com/2025/day/3
+
+local DEBUG = true
+
+function debug(msg)
+	if DEBUG then
+		print(msg)
+	end
+end
+
+function MaxJolt(Battery)
+	local b = {}
+	local firstdigit = 0
+	local seconddigit = 0
+	local maxdigit = 0
+
+	lastdigit = tonumber(string.sub(Battery, -1))
+	debug("lastdigit " .. lastdigit)
+
+	BatteryNoLast = string.sub(Battery, 0, -2)
+	BatteryNoLast:gsub(".", function(c)
+		table.insert(b, c)
+		return c
+	end)
+
+	for key, value in pairs(b) do
+		checkdigit = tonumber(value)
+		if firstdigit < checkdigit then
+			firstdigit = checkdigit
+		elseif seconddigit < checkdigit then
+			seconddigit = checkdigit
+		end
+	end
+	if seconddigit < lastdigit then
+		seconddigit = lastdigit
+	end
+	debug("First " .. firstdigit)
+	debug("Second " .. seconddigit)
+	return tostring(firstdigit) .. tostring(seconddigit)
+end
+
+function TestMaxJolt(Battery, Test)
+	local MJ = MaxJolt(Battery)
+	if MJ == Test then
+		print("WIN  - " .. Battery .. " " .. MJ .. " == " .. Test)
+	else
+		print("FAIL - " .. Battery .. " " .. MJ .. " != " .. Test)
+	end
+end
+
+print("# Self Test")
+TestMaxJolt("987654321111111", "98")
+TestMaxJolt("811111111111119", "89")
+TestMaxJolt("234234234234278", "78")
+TestMaxJolt("818181911112111", "89")