1 files changed, 20 insertions(+), 20 deletions(-)

M 2023/14.lua

@@ 1,32 1,31 @@
-local grid, R, C, E = {}, string.byte('O#.', 1, 3)
+local grid, size, R, C, E = {}, 0, string.byte('O#.', 1, -1)
 io.input(arg[1])
 for line in io.lines() do
-	table.insert(grid, {string.byte(line, 1, #line)})
+	size = size + 1
+	grid[size] = {string.byte(line, 1, #line)}
 end
-assert(#grid == #grid[1])
+assert(size == #grid[1])
 
 local function key()
 	local k = {}
-	for _, row in ipairs(grid) do
-		table.insert(k, string.pack('z', string.char(table.unpack(row))))
+	for y, row in ipairs(grid) do
+		k[y] = string.char(table.unpack(row))
 	end
 	return table.concat(k)
 end
-
-local function load()
-	local l = 0
-	for y, row in ipairs(grid) do
-		for _, c in ipairs(row) do
-			if c == R then l = l + #grid - y + 1 end
+local function load(k)
+	local i, l = 1, 0
+	for y = size, 1, -1 do
+		for _ = 1, size do
+			if string.byte(k, i) == R then l = l + y end
+			i = i + 1
 		end
 	end
 	return l
 end
 
-local i, cycles, seen, cubes, last, ans1 = 1, 1000000000, {}, {}
-local size = #grid
-local cubes = {}
-while i <= cycles do
+local cycles, seen, cubes, last, ans1, ans2 = 1000000000, {}, {}
+for i = 1, cycles do
 	for x = 1, size do cubes[x] = 0 end
 	for y = 1, size do
 		local row = grid[y]


@@ 42,7 41,7 @@ while i <= cycles do
 			end
 		end
 	end
-	if i == 1 then ans1 = load() end
+	if i == 1 then ans1 = load(key()) end
 	for y = 1, size do
 		local row, cube = grid[y], 0
 		for x = 1, size do


@@ 87,10 86,11 @@ while i <= cycles do
 	if not last then
 		local k = key()
 		last = seen[k]
-		if last then cycles = (cycles - last) % (i - last) + i end
-		seen[k] = i
+		if last then
+			ans2 = load(seen[(cycles - last) % (i - last) + last])
+			break
+		end
+		seen[k], seen[i] = i, k
 	end
-	i = i + 1
 end
-local ans2 = load()
 print(ans1, ans2)