Revision of ribbons.ml

1 file changed, 50 insertions

ribbons.ml(file created)

		@@ -0,0 +1,50 @@
1	+	type open_ribbon = [`Open of int]
2	+	type looped_ribbon = [`Looped]
3	+	type ribbon =
4	+	[
5	+	\| `Open of int
6	+	\| `Looped
7	+	]
8	+
9	+	let tie a b : ribbon =
10	+	match a, b with
11	+	\| (`Open x, `Open y) when x == y ->
12	+	`Looped
13	+	\| (`Open x, `Open y) ->
14	+	`Open x
15	+
16	+	let ribbon_id =
17	+	let id = ref 0 in
18	+	fun () -> incr id; !id
19	+
20	+	let make_ribbon () =
21	+	`Open (ribbon_id ())
22	+
23	+	let drop f x = f ()
24	+
25	+	let swap_and_pop dynarray i =
26	+	dynarray \|> Dynarray.get_last \|> Dynarray.set dynarray i ;
27	+	dynarray \|> Dynarray.remove_last
28	+
29	+	let loop_ribbons () =
30	+	let loops = ref 0 in
31	+	let ribbons = Dynarray.init 100 (drop make_ribbon) in
32	+	while Dynarray.is_empty ribbons \|> not do
33	+	let i = ribbons \|> Dynarray.length \|> Random.int in
34	+	let j = ribbons \|> Dynarray.length \|> Random.int in
35	+	match tie (Dynarray.get ribbons i) (Dynarray.get ribbons j) with
36	+	\| `Open id ->
37	+	Dynarray.set ribbons i (`Open id) ;
38	+	swap_and_pop ribbons j
39	+	\| `Looped ->
40	+	incr loops ;
41	+	swap_and_pop ribbons i ;
42	+	done;
43	+	!loops
44	+
45	+	let run_simulations runs =
46	+	let acc = ref 0 in
47	+	for i = 1 to runs do
48	+	acc := !acc + loop_ribbons ()
49	+	done;
50	+	Float.of_int !acc /. Float.of_int runs

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