1 files changed, 38 insertions, 0 deletions
diff --git a/05/2.lua b/05/2.lua
new file mode 100644
index 0000000..a132630
--- /dev/null
+++ b/05/2.lua
@@ -0,0 +1,38 @@
+#!/usr/bin/env lua
+
+local stacks
+for line in io.lines() do
+	if not stacks then -- first line
+		stacks = {}
+		local num_stacks = math.ceil(#line / 4)
+		for i = 1, num_stacks do
+			stacks[i] = {}
+		end
+	end
+	if line:sub(2,2) == "1" then
+		break -- end of crates
+	end
+	for i = 1, #line, 4 do
+		local letter = line:sub(i+1,i+1)
+		if letter ~= " " then
+			table.insert(stacks[math.ceil(i/4)],1,letter)
+		end
+	end
+end
+for line in io.lines() do break end -- empty line between crates and orders
+for line in io.lines() do
+	local amt, from, to = line:match("move (%d+) from (%d+) to (%d+)")
+	amt, from, to = tonumber(amt), tonumber(from), tonumber(to)
+	local crates = {}
+	for i = 1, amt do
+		table.insert(crates, table.remove(stacks[from]))
+	end
+	for i = 1, #crates do
+		table.insert(stacks[to], table.remove(crates))
+	end
+end
+local msg = {}
+for _,c in pairs(stacks) do
+	table.insert(msg,c[#c])
+end
+print(table.concat(msg))