day 21 part 2 wip

day21/part2.lua

@@ -0,0 +1,48 @@
+#!/usr/bin/env luajit
+require("utils")
+
+local f = io.open(arg[3])
+local fst = tonumber(string.match(f:read("*l"), "Player 1 starting position: (.*)")) - 1
+local snd = tonumber(string.match(f:read("*l"), "Player 2 starting position: (.*)")) - 1
+f:close()
+
+local function index(score1, score2, loc1, loc2)
+	return loc2 + 10 * (loc1 + 30 * (score2 + 30 * score1))
+end
+
+local function deindex(index)
+	local lo2, loc1, score2, score1
+	loc2, index = index % 10, math.floor(index / 10)
+	loc1, index = index % 30, math.floor(index / 30)
+	score2, index = index % 30, math.floor(index / 30)
+	score1 = index
+	return score1, score2, loc1, loc2
+end
+
+local poss = { [index(0, 0, fst, snd)] = 1 }
+local size = 1
+local c1, c2 = 0, 0
+while size > 0 do
+	print(size)
+	local newposs = {}
+	size = 0
+	for i, c in pairs(poss) do
+		local s1, s2, l1, l2 = deindex(i)
+		print(s1, s2, l1, l2, c)
+		if s2 >= 21 then
+			c2 = c2 + c
+		else
+			local i3 = index(s2, s1 + 3, l2, (l1 + 3) % 10); newposs[i3] = (newposs[i3] or 0) + 1 * c
+			local i4 = index(s2, s1 + 4, l2, (l1 + 4) % 10); newposs[i4] = (newposs[i4] or 0) + 3 * c
+			local i5 = index(s2, s1 + 5, l2, (l1 + 5) % 10); newposs[i5] = (newposs[i5] or 0) + 6 * c
+			local i6 = index(s2, s1 + 6, l2, (l1 + 6) % 10); newposs[i6] = (newposs[i6] or 0) + 7 * c
+			local i7 = index(s2, s1 + 7, l2, (l1 + 7) % 10); newposs[i7] = (newposs[i7] or 0) + 6 * c
+			local i8 = index(s2, s1 + 8, l2, (l1 + 8) % 10); newposs[i8] = (newposs[i8] or 0) + 3 * c
+			local i9 = index(s2, s1 + 9, l2, (l1 + 9) % 10); newposs[i9] = (newposs[i9] or 0) + 1 * c
+			size = size + 27 * c
+		end
+	end
+	poss = newposs
+	c1, c2 = c2, c1
+end
+print(c1, c2)