day 4

day04/part1.lua

@@ -0,0 +1,71 @@
+function split(text, sep)
+	local parts = {}
+	local start = 0
+	local from, to = text:find(sep)
+	while from ~= nil do
+		table.insert(parts, text:sub(start, from - 1))
+		text = text:sub(to + 1)
+		from, to = text:find(sep)
+	end
+	table.insert(parts, text)
+	return parts
+end
+
+local f = io.open(arg[3])
+local numbers = split(f:read("*l"), ",")
+local line = f:read("*l")
+local boards = {}
+while line ~= nil do
+	local board = {}
+	for r = 1, 5 do
+		line = f:read("*l")
+		while line:byte(1) == string.byte(" ", 1) do
+			line = line:sub(2)
+		end
+		board[r] = split(line, " +")
+	end
+	table.insert(boards, board)
+	line = f:read("*l")
+end
+
+local i, complete = 0, nil
+while complete == nil and i <= #numbers do
+	local number = numbers[i]
+	local tests = {}
+	for b, board in pairs(boards) do
+		for r, row in pairs(board) do
+			for c, col in pairs(row) do
+				if col == number then
+					row[c] = nil
+					table.insert(tests, {b, r, c})
+				end
+			end
+		end
+	end
+
+	for t, test in pairs(tests) do
+		local board, row, col = unpack(test)
+		local j, rownils, colnils = 1, 0, 0
+		while j <= 5 and (rownils == 0 or colnils == 0) do
+			if boards[board][row][j] ~= nil then rownils = rownils + 1 end
+			if boards[board][j][col] ~= nil then colnils = colnils + 1 end
+			j = j + 1
+		end
+		if rownils == 0 or colnils == 0 then
+			complete = boards[board]
+		end
+	end
+
+	i = i + 1
+end
+
+print(numbers[i - 1])
+local sum = 0
+for r = 1, 5 do
+	for c = 1, 5 do
+		io.write((complete[r][c] or "nil") .. " ")
+		sum = sum + (complete[r][c] or 0)
+	end
+	io.write("\n")
+end
+print(numbers[i - 1] * sum)

day04/part2.lua

@@ -0,0 +1,74 @@
+function split(text, sep)
+	local parts = {}
+	local start = 0
+	local from, to = text:find(sep)
+	while from ~= nil do
+		table.insert(parts, text:sub(start, from - 1))
+		text = text:sub(to + 1)
+		from, to = text:find(sep)
+	end
+	table.insert(parts, text)
+	return parts
+end
+
+local f = io.open(arg[3])
+local numbers = split(f:read("*l"), ",")
+local line = f:read("*l")
+local boards = {}
+while line ~= nil do
+	local board = {}
+	for r = 1, 5 do
+		line = f:read("*l")
+		while line:byte(1) == string.byte(" ", 1) do
+			line = line:sub(2)
+		end
+		board[r] = split(line, " +")
+	end
+	table.insert(boards, board)
+	line = f:read("*l")
+end
+
+function finished(board, row, col)
+	local j, rowints, colints = 1, 0, 0
+	while j <= 5 and (rowints == 0 or colints == 0) do
+		if board[row][j] ~= nil then rowints = rowints + 1 end
+		if board[j][col] ~= nil then colints = colints + 1 end
+		j = j + 1
+	end
+	return rowints == 0 or colints == 0
+end
+
+local i = 1
+local complete
+while #boards > 0 and i <= #numbers do
+	local number = numbers[i]
+	local nboards = {}
+	for b, board in pairs(boards) do
+		complete = board
+		local hasfinished = false
+		for r, row in pairs(board) do
+			for c, col in pairs(row) do
+				if col == number then
+					row[c] = nil
+					if finished(board, r, c) then
+						hasfinished = true
+					end
+				end
+			end
+		end
+		if not hasfinished then
+			table.insert(nboards, board)
+		end
+	end
+	boards = nboards
+
+	i = i + 1
+end
+
+local sum = 0
+for r = 1, 5 do
+	for c = 1, 5 do
+		sum = sum + (complete[r][c] or 0)
+	end
+end
+print(numbers[i - 1] * sum)