From a0a5e5f447115bf740d6792ff5278c000c2563a6 Mon Sep 17 00:00:00 2001
From: Vladan Popovic <vladanovic@gmail.com>
Date: Wed, 9 Dec 2020 00:51:24 +0100
Subject: [PATCH] day 8

---
 day8.input | 636 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 day8.ml    |  57 +++++
 day8.test  |   9 +
 3 files changed, 702 insertions(+)
 create mode 100644 day8.input
 create mode 100644 day8.ml
 create mode 100644 day8.test

diff --git a/day8.input b/day8.input
new file mode 100644
index 0000000..b97230b
--- /dev/null
+++ b/day8.input
@@ -0,0 +1,636 @@
+acc -13
+jmp +37
+acc -19
+jmp +1
+jmp +1
+jmp +413
+acc +10
+jmp +194
+jmp +587
+jmp +388
+acc +48
+nop +284
+acc +35
+jmp +239
+acc +0
+jmp +58
+acc +22
+acc +45
+acc +25
+acc +23
+jmp +544
+jmp +610
+nop +273
+jmp +554
+jmp +584
+acc +30
+jmp +481
+acc +29
+jmp +342
+acc +9
+acc +23
+nop +377
+jmp +483
+acc +33
+jmp +128
+nop +560
+nop +437
+jmp +485
+acc +2
+acc +30
+jmp +456
+acc +0
+acc -15
+nop +126
+acc +47
+jmp +299
+acc +36
+acc +9
+jmp -21
+acc +10
+acc +26
+acc -3
+acc +31
+jmp +337
+nop +517
+jmp +303
+acc +20
+nop -43
+acc +30
+acc +24
+jmp +348
+jmp +158
+acc +23
+acc +16
+acc +40
+jmp +1
+jmp +465
+acc +12
+jmp +276
+acc +0
+acc +32
+acc +43
+jmp +487
+acc +40
+acc +49
+nop +540
+jmp +455
+acc +24
+jmp +481
+acc +30
+nop +256
+acc +29
+acc +14
+jmp +390
+jmp +1
+acc -3
+jmp +1
+jmp +295
+acc +6
+acc +46
+acc +16
+nop +128
+jmp -38
+acc +0
+acc +16
+acc +10
+jmp +185
+acc -19
+acc +0
+acc +23
+acc -16
+jmp +180
+acc +14
+jmp +1
+acc +31
+acc -4
+jmp +439
+jmp +204
+acc +50
+acc +12
+nop +154
+jmp +474
+acc -16
+jmp +511
+acc +6
+acc +32
+jmp +504
+acc +17
+acc +21
+acc -18
+jmp +298
+acc -17
+acc +16
+acc +4
+acc +18
+jmp +18
+acc -10
+acc +26
+acc +36
+jmp +166
+nop -109
+jmp +266
+acc -9
+jmp +306
+nop +324
+acc +16
+acc +33
+acc +18
+jmp -50
+acc +25
+jmp +196
+acc +21
+jmp +308
+jmp +38
+acc +27
+jmp -48
+acc +14
+acc +46
+acc +48
+acc +15
+jmp +223
+acc +0
+acc +12
+jmp -115
+acc +19
+acc +27
+acc +30
+jmp +377
+jmp -144
+jmp +231
+acc +1
+jmp +410
+acc +41
+jmp +138
+acc -13
+acc -8
+acc -7
+acc +25
+jmp +366
+acc +8
+jmp +182
+acc +2
+nop +104
+acc +24
+acc +21
+jmp -43
+acc -8
+acc +37
+acc +23
+jmp +292
+jmp +365
+acc +33
+nop -144
+acc -10
+jmp +387
+acc +13
+acc -6
+acc -12
+nop +134
+jmp +345
+acc +5
+acc +16
+acc +35
+acc +50
+jmp +250
+acc +46
+jmp +105
+acc -6
+nop -152
+jmp +233
+jmp -88
+acc +39
+jmp +59
+acc -4
+acc +47
+jmp +165
+acc +32
+acc +49
+acc +24
+jmp +344
+acc -5
+acc +3
+jmp +359
+acc +27
+jmp +72
+acc +0
+acc +16
+acc +40
+jmp +98
+acc +2
+acc +23
+acc +48
+acc +2
+jmp -33
+jmp -186
+acc +27
+nop -83
+acc +2
+acc +19
+jmp -141
+acc +39
+acc +34
+acc +33
+jmp +282
+jmp +306
+acc +12
+jmp +317
+acc +32
+acc +50
+acc +17
+jmp +52
+acc +3
+acc +35
+jmp +328
+acc +26
+nop +163
+acc +6
+acc +19
+jmp +154
+acc +4
+jmp +1
+jmp +373
+acc -12
+acc +47
+jmp +1
+jmp -234
+acc +45
+acc +46
+acc -14
+acc +50
+jmp -134
+acc +26
+jmp +128
+jmp +233
+acc +23
+nop -133
+jmp -154
+jmp +260
+acc +21
+acc +14
+nop -89
+acc +9
+jmp -113
+acc +10
+acc +5
+jmp +127
+acc -9
+acc +2
+jmp +286
+nop +274
+jmp +93
+acc +46
+acc +36
+jmp +53
+acc +30
+jmp -126
+acc +11
+acc +11
+acc +23
+jmp +296
+nop -100
+jmp +304
+jmp +219
+acc +16
+jmp -93
+acc +12
+jmp +1
+jmp +205
+acc +6
+acc -11
+jmp +202
+jmp +107
+jmp +1
+jmp -224
+acc +24
+acc +50
+acc +37
+jmp +45
+acc +25
+acc -15
+jmp -151
+jmp +1
+acc +47
+jmp -196
+jmp +1
+jmp +300
+jmp +116
+acc +39
+acc +0
+nop -176
+acc -7
+jmp -53
+acc +20
+nop -216
+nop +291
+jmp +38
+acc +0
+acc +32
+acc -19
+jmp -28
+jmp -176
+acc +33
+acc +11
+acc +47
+nop -58
+jmp -203
+acc +48
+acc +50
+acc +41
+jmp -315
+acc -12
+acc +23
+acc +32
+jmp +210
+acc +46
+acc -11
+acc -16
+jmp +103
+acc +25
+nop +95
+acc +9
+jmp -117
+nop +18
+acc -19
+acc +38
+jmp -130
+acc +22
+jmp +25
+nop +201
+nop +205
+acc +14
+jmp -124
+jmp -46
+acc +9
+jmp -257
+acc -19
+acc -17
+acc +36
+acc +24
+jmp -210
+jmp -231
+acc +40
+jmp +46
+nop -192
+acc -13
+acc +7
+acc +33
+jmp +103
+acc +18
+acc +37
+acc -14
+jmp -11
+acc +12
+nop -240
+acc +35
+acc +33
+jmp -274
+acc -9
+acc +24
+jmp -128
+nop -129
+acc -17
+jmp -62
+acc +0
+acc +42
+nop +116
+jmp -44
+acc +16
+jmp +179
+acc -8
+acc +8
+jmp -149
+acc +39
+acc +2
+acc +14
+acc +12
+jmp -373
+jmp +76
+jmp -232
+jmp -385
+acc +22
+acc +41
+acc +28
+jmp -179
+acc +0
+acc +22
+acc +15
+jmp -291
+acc -18
+jmp -222
+acc +45
+acc -15
+jmp +61
+acc +10
+acc +16
+acc +43
+jmp +177
+acc +43
+acc -12
+acc +20
+acc +27
+jmp -13
+acc -14
+jmp -336
+nop -158
+acc +3
+nop -409
+acc +17
+jmp -257
+acc +0
+nop +124
+jmp +1
+jmp +117
+jmp -179
+acc -17
+acc -2
+jmp +1
+jmp -37
+acc +42
+jmp +175
+acc -9
+acc +12
+acc +4
+jmp +69
+acc -7
+jmp +1
+acc +32
+jmp +54
+jmp -444
+acc +7
+jmp -87
+acc -6
+nop -323
+acc +47
+acc -5
+jmp -143
+jmp +1
+nop -44
+acc +27
+acc +21
+jmp -184
+jmp -404
+jmp -70
+acc +32
+jmp -13
+acc +0
+nop -452
+acc +1
+acc +31
+jmp -77
+jmp -401
+acc +42
+jmp -428
+nop -120
+acc -17
+nop -75
+acc +6
+jmp +20
+jmp -291
+acc +7
+jmp +37
+acc +10
+acc +15
+jmp +1
+acc +11
+jmp -363
+acc -14
+nop -321
+jmp -40
+acc +41
+acc +31
+jmp +58
+jmp -493
+acc +32
+acc -10
+acc +44
+jmp -211
+acc +47
+acc +23
+jmp -241
+jmp -224
+acc -1
+jmp -350
+acc +8
+jmp -280
+acc -19
+acc +0
+acc +17
+jmp -274
+acc +27
+acc +11
+jmp -82
+acc +48
+acc +27
+jmp -518
+acc +3
+jmp -124
+jmp +1
+jmp -490
+acc +41
+jmp -238
+acc -6
+jmp -386
+jmp -189
+acc -11
+jmp +80
+acc -8
+acc +9
+nop -99
+jmp +56
+acc -18
+jmp -83
+acc +28
+acc +13
+jmp -228
+acc +32
+acc +34
+acc +3
+jmp -272
+nop -410
+acc +13
+acc -17
+jmp -236
+acc +45
+acc +0
+acc +19
+nop +29
+jmp +38
+jmp -75
+acc +7
+acc +33
+acc +40
+jmp -180
+jmp -557
+acc +22
+jmp -249
+acc +44
+acc +45
+acc +2
+acc -19
+jmp -537
+acc +44
+acc +32
+acc -14
+acc +39
+jmp -406
+jmp -488
+acc +14
+acc +41
+jmp -327
+acc +17
+acc +25
+nop -573
+acc +0
+jmp -563
+acc +18
+nop -282
+acc +13
+acc +45
+jmp -325
+acc +41
+acc -10
+nop -47
+nop -223
+jmp -155
+acc +14
+acc +23
+jmp +23
+acc +21
+nop -229
+acc +27
+acc -5
+jmp -95
+acc +2
+acc -10
+nop -451
+jmp -393
+jmp -406
+acc +42
+acc +18
+acc +49
+jmp -307
+acc -11
+jmp +1
+jmp -424
+jmp -192
+acc +49
+acc -1
+acc -17
+jmp -355
+jmp -268
+nop -320
+acc +1
+jmp -134
+acc +46
+jmp -564
+acc +40
+acc +29
+acc +13
+nop -285
+jmp -272
+acc +19
+acc -14
+acc +25
+acc +18
+jmp +1
diff --git a/day8.ml b/day8.ml
new file mode 100644
index 0000000..36caccd
--- /dev/null
+++ b/day8.ml
@@ -0,0 +1,57 @@
+let read name =
+    let ic = open_in name in
+    let try_read () =
+        try Some (input_line ic)
+        with End_of_file -> None in
+    let rec loop acc =
+        match try_read () with
+        | Some s -> loop (s::acc)
+        | None -> close_in ic; acc in
+    List.rev (loop [])
+
+
+let build lines =
+    let rec aux res idx = function
+        | h :: t -> let [instr; value] = String.split_on_char ' ' h in
+                                         let () = res.(idx) <- (0, instr, int_of_string value) in
+                                         aux res (idx + 1) t
+        | [] -> res in
+    aux (Array.make (List.length lines) (0, "nop", 0)) 0 lines
+
+
+let rec step pc acc instructions =
+    let (n, instr, v) = instructions.(pc) in
+    let () = instructions.(pc) <- (n + 1, instr, v) in
+    match instr with
+    | "nop" -> (n + 1, pc + 1, acc)
+    | "acc" -> (n + 1, pc + 1, acc + v)
+    | "jmp" -> step (pc + v) acc instructions
+    | _ -> raise (Failure "unreachable")
+
+
+let run instructions =
+    let rec aux pc acc instructions =
+        match step pc acc instructions with
+        | (2, _, _) -> raise (Failure (Printf.sprintf "Loop detected with accumulator %d!" acc))
+        | (_, pc, result) when pc = (Array.length instructions - 1) -> result
+        | (_, pc, acc_) -> aux pc acc_ instructions
+    in aux 0 0 instructions
+
+
+let rec swap_from idx ins =
+    match ins.(idx) with
+    | (_, "nop", v) when v <> 0 -> let () = ins.(idx) <- (0, "jmp", v) in (idx + 1, ins)
+    | (_, "jmp", v) -> let () = ins.(idx) <- (0, "nop", v) in (idx + 1, ins)
+    | _ -> swap_from (idx + 1) ins
+
+
+let fix instructions =
+    let rec aux idx ins instructions =
+        try run ins
+        with e -> let (i, ins) = swap_from idx (Array.copy instructions) in
+                  aux i ins instructions
+    in aux 0 (Array.copy instructions) instructions
+
+let () = try let _ = read "day8.input" |> build |> run in ()
+         with Failure msg -> print_endline msg
+let () = print_endline (string_of_int (read "day8.input" |> build |> fix))
diff --git a/day8.test b/day8.test
new file mode 100644
index 0000000..178df53
--- /dev/null
+++ b/day8.test
@@ -0,0 +1,9 @@
+nop +0
+acc +1
+jmp +4
+acc +3
+jmp -3
+acc -99
+acc +1
+jmp -4
+acc +6