Data commit

Task/Ackermann-function/Lua/ackermann-function-2.lua

@@ -0,0 +1,38 @@
+#!/usr/bin/env luajit
+local gmp = require 'gmp' ('libgmp')
+local mpz, 		z_mul, 		z_add, 		z_add_ui, 		z_set_d =
+	gmp.types.z, gmp.z_mul,	gmp.z_add,	gmp.z_add_ui, 	gmp.z_set_d
+local z_cmp, 	z_cmp_ui, 		z_init_d, 			z_set=
+	gmp.z_cmp,	gmp.z_cmp_ui, 	gmp.z_init_set_d, 	gmp.z_set
+local printf = gmp.printf
+
+local function ack(i,n)
+	local nxt=setmetatable({},  {__index=function(t,k) local z=mpz() z_init_d(z, 0) t[k]=z return z end})
+	local goal=setmetatable({}, {__index=function(t,k) local o=mpz() z_init_d(o, 1) t[k]=o return o end})
+	goal[i]=mpz() z_init_d(goal[i], -1)
+	local v=mpz() z_init_d(v, 0)
+	local ic
+	local END=n+1
+	local ntmp,gtmp
+	repeat
+		ic=0
+		ntmp,gtmp=nxt[ic], goal[ic]
+		z_add_ui(v, ntmp, 1)
+		while z_cmp(ntmp, gtmp) == 0 do
+			z_set(gtmp,v)
+			z_add_ui(ntmp, ntmp, 1)
+			nxt[ic], goal[ic]=ntmp, gtmp
+			ic=ic+1
+			ntmp,gtmp=nxt[ic], goal[ic]
+		end
+		z_add_ui(ntmp, ntmp, 1)
+		nxt[ic]=ntmp
+	until z_cmp_ui(nxt[i], END) == 0
+	return v
+end
+
+if #arg<1 then
+	print("Ackermann: "..arg[0].." <num1> [num2]")
+else
+	printf("%Zd\n", ack(tonumber(arg[1]), arg[2] and tonumber(arg[2]) or 0))
+end