Day 4 done

2025/Day4/Day4_first.lua

@@ -0,0 +1,108 @@
+#!/usr/bin/lua
+--Advent of Code - 2025 - Day 4
+--
+--https://adventofcode.com/2025/day/4
+
+-- Problem, find space for forklift to move
+-- Tasks
+-- [ ] Load Paper roll in array
+-- [ ] Walk through Array finding spots
+--
+--
+--local input_file = "test"
+local input_file = "full"
+local warehouse = {}
+
+local row = 0
+local col = 0
+
+for line in io.lines(input_file) do
+	row = row + 1
+	warehouse[row] = {}
+	col = 0
+	for location in line:gmatch(".") do
+		col = col + 1
+		warehouse[row][col] = location
+	end
+end
+
+function space_for_forklift(warehouse, x, y)
+	-- I'm making the assuption here that all rows have the same columns
+	-- normally I would say write a selfcheck to confirm input is sound
+	local rows = table.getn(warehouse)
+	local columns = table.getn(warehouse[1])
+	local spaces = 0
+
+	if warehouse[x][y] ~= "@" then
+		-- No paper roll, so skip
+		--print("warehouse check " .. x .. "," .. y .. " no paper roll")
+		return false
+	end
+
+	local freespace = 0
+	local rolls = 0
+	for rowskim = -1, 1 do
+		if warehouse[x + rowskim] == nil then
+			freespace = freespace + 3
+		else
+			for colskim = -1, 1 do
+				local w = warehouse[x + rowskim][y + colskim]
+				--print("checking " .. (x + rowskim) .. "," .. (y + colskim) .. "=" .. w)
+				if not (rowskim == 0 and colskim == 0) then
+					if w == "@" or w == "X" then
+						rolls = rolls + 1
+					else
+						freespace = freespace + 1
+					end
+				end
+			end
+		end
+	end
+	if rolls < 4 then
+		--print("warehouse check " .. x .. "," .. y .. " found space")
+		warehouse[x][y] = "X"
+		return true
+	else
+		--print("warehouse check " .. x .. "," .. y .. " no space")
+		return false
+	end
+end
+
+function remove_rolls(warehouse)
+	local maxrows = table.getn(warehouse)
+	local maxcolumns = table.getn(warehouse[1])
+	for r = 1, maxrows do
+		for c = 1, maxcolumns do
+			if warehouse[r][c] == "X" then
+				warehouse[r][c] = "."
+			end
+		end
+	end
+end
+
+-- print(space_for_forklift(warehouse, 1, 1))
+-- print(space_for_forklift(warehouse, 1, 3))
+-- print(space_for_forklift(warehouse, 2, 1))
+-- print(space_for_forklift(warehouse, 3, 7))
+function countrolls(warehouse)
+	local maxrows = table.getn(warehouse)
+	local maxcolumns = table.getn(warehouse[1])
+	local forkliftaccess = 0
+	for r = 1, maxrows do
+		for c = 1, maxcolumns do
+			if space_for_forklift(warehouse, r, c) then
+				forkliftaccess = forkliftaccess + 1
+			end
+		end
+	end
+	return forkliftaccess
+end
+
+totalrolls = 0
+for I = 1, 100 do
+	cr = countrolls(warehouse)
+	totalrolls = totalrolls + cr
+	print("Loop " .. I .. ": " .. cr .. " Rolls removed")
+	remove_rolls(warehouse)
+end
+print("Total rolls removed " .. totalrolls)