summary refs log tree commit diff stats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--2020/day-09/README.org179
-rwxr-xr-x2020/day-09/day-09.raku52
-rw-r--r--2020/day-09/input1000
3 files changed, 1231 insertions, 0 deletions
diff --git a/2020/day-09/README.org b/2020/day-09/README.org
new file mode 100644
index 0000000..db1eeab
--- /dev/null
+++ b/2020/day-09/README.org
@@ -0,0 +1,179 @@
+#+SETUPFILE: ~/.emacs.d/org-templates/level-3.org
+#+HTML_LINK_UP: ../../index.html#2020
+#+OPTIONS: toc:1
+#+EXPORT_FILE_NAME: index
+#+TITLE: Day 09 - Encoding Error
+
+* Puzzle
+- This puzzle is taken from: https://adventofcode.com/2020/day/9
+
+With your neighbor happily enjoying their video game, you turn your
+attention to an open data port on the little screen in the seat in front
+of you.
+
+Though the port is non-standard, you manage to connect it to your
+computer through the clever use of several paperclips. Upon connection,
+the port outputs a series of numbers (your puzzle input).
+
+The data appears to be encrypted with the eXchange-Masking Addition
+System (XMAS) which, conveniently for you, is an old cypher with an
+important weakness.
+
+XMAS starts by transmitting a preamble of 25 numbers. After that, each
+number you receive should be the sum of any two of the 25 immediately
+previous numbers. The two numbers will have different values, and there
+might be more than one such pair.
+
+For example, suppose your preamble consists of the numbers 1 through 25
+in a random order. To be valid, the next number must be the sum of two
+of those numbers:
+
+- 26 would be a valid next number, as it could be 1 plus 25 (or many
+  other pairs, like 2 and 24).
+- 49 would be a valid next number, as it is the sum of 24 and 25.
+- 100 would not be valid; no two of the previous 25 numbers sum to 100.
+- 50 would also not be valid; although 25 appears in the previous 25
+  numbers, the two numbers in the pair must be different.
+
+Suppose the 26th number is 45, and the first number (no longer an
+option, as it is more than 25 numbers ago) was 20. Now, for the next
+number to be valid, there needs to be some pair of numbers among 1-19,
+21-25, or 45 that add up to it:
+
+- 26 would still be a valid next number, as 1 and 25 are still within
+  the previous 25 numbers.
+- 65 would not be valid, as no two of the available numbers sum to it.
+- 64 and 66 would both be valid, as they are the result of 19+45 and
+  21+45 respectively.
+
+Here is a larger example which only considers the previous 5 numbers
+(and has a preamble of length 5):
+#+BEGIN_SRC
+35
+20
+15
+25
+47
+40
+62
+55
+65
+95
+102
+117
+150
+182
+127
+219
+299
+277
+309
+576
+#+END_SRC
+
+In this example, after the 5-number preamble, almost every number is the
+sum of two of the previous 5 numbers; the only number that does not
+follow this rule is 127.
+
+The first step of attacking the weakness in the XMAS data is to find the
+first number in the list (after the preamble) which is not the sum of
+two of the 25 numbers before it. What is the first number that does not
+have this property?
+** Part 2
+The final step in breaking the XMAS encryption relies on the invalid
+number you just found: you must find a contiguous set of at least two
+numbers in your list which sum to the invalid number from step 1.
+
+Again consider the above example:
+#+BEGIN_SRC
+35
+20
+15
+25
+47
+40
+62
+55
+65
+95
+102
+117
+150
+182
+127
+219
+299
+277
+309
+576
+#+END_SRC
+
+In this list, adding up all of the numbers from 15 through 40 produces
+the invalid number from step 1, 127. (Of course, the contiguous set of
+numbers in your actual list might be much longer.)
+
+To find the encryption weakness, add together the smallest and largest
+number in this contiguous range; in this example, these are 15 and 47,
+producing 62.
+
+What is the encryption weakness in your XMAS-encrypted list of numbers?
+* Solution
+Second part is dependent on the first part so we find the invalid number
+in all cases. =%invalid= stores the invalid number along with it's index.
+We check all possible combinations.
+
+I'm too tired to explain this in detail, maybe I'll add explanation
+later. Also, the solution isn't good.
+#+BEGIN_SRC raku
+my @numbers = "input".IO.lines>>.Int;
+my Int $solution;
+
+my Int $preamble_length = 25;
+my Int %invalid;
+
+MAIN: for @numbers.kv -> $idx, $num {
+    next if $idx < $preamble_length;
+
+    my @preamble = @numbers[$idx - $preamble_length..$idx - 1].sort;
+
+    my Bool $valid;
+    while pop @preamble -> $num_1 {
+        my $diff = $num - $num_1;
+        for @preamble -> $num_2 {
+            if $num_2 == $diff {
+                $valid = True;
+                next MAIN;
+            }
+        }
+    }
+
+    unless $valid {
+        %invalid<num> = $num;
+        %invalid<idx> = $idx;
+        $solution = %invalid<num> if $part == 1;
+        last MAIN;
+    }
+}
+
+if $part == 2 {
+    ...
+}
+
+say "Part $part: ", $solution;
+#+END_SRC
+** Part 2
+We brute force the second part too.
+#+BEGIN_SRC raku
+my @set = @numbers[0..%invalid<idx> - $preamble_length - 1];
+
+PART2: for @set.elems - 1 ... 0 -> $idx_1 {
+    for @set.elems - 1 ... 0 -> $idx_2 {
+        my $sum = [+] @set[$idx_1..$idx_2];
+        if $sum == %invalid<num> {
+            my @tmp = @set[$idx_1..$idx_2].sort;
+            $solution = @tmp[0] + @tmp[*-1];
+            last PART2;
+        }
+    }
+}
+#+END_SRC
diff --git a/2020/day-09/day-09.raku b/2020/day-09/day-09.raku
new file mode 100755
index 0000000..e9b6683
--- /dev/null
+++ b/2020/day-09/day-09.raku
@@ -0,0 +1,52 @@
+#!/usr/bin/env raku
+
+sub MAIN (
+    Int $part where * == 1|2 = 1 #= part to run (1 or 2)
+) {
+    my @numbers = "input".IO.lines>>.Int;
+    my Int $solution;
+
+    my Int $preamble_length = 25;
+    my Int %invalid;
+
+    MAIN: for @numbers.kv -> $idx, $num {
+        next if $idx < $preamble_length;
+
+        my @preamble = @numbers[$idx - $preamble_length..$idx - 1].sort;
+
+        my Bool $valid;
+        while pop @preamble -> $num_1 {
+            my $diff = $num - $num_1;
+            for @preamble -> $num_2 {
+                if $num_2 == $diff {
+                    $valid = True;
+                    next MAIN;
+                }
+            }
+        }
+
+        unless $valid {
+            %invalid<num> = $num;
+            %invalid<idx> = $idx;
+            $solution = %invalid<num> if $part == 1;
+            last MAIN;
+        }
+    }
+
+    if $part == 2 {
+        my @set = @numbers[0..%invalid<idx> - $preamble_length - 1];
+
+        PART2: for @set.elems - 1 ... 0 -> $idx_1 {
+            for @set.elems - 1 ... 0 -> $idx_2 {
+                my $sum = [+] @set[$idx_1..$idx_2];
+                if $sum == %invalid<num> {
+                    my @tmp = @set[$idx_1..$idx_2].sort;
+                    $solution = @tmp[0] + @tmp[*-1];
+                    last PART2;
+                }
+            }
+        }
+    }
+
+    say "Part $part: ", $solution;
+}
diff --git a/2020/day-09/input b/2020/day-09/input
new file mode 100644
index 0000000..afaf5cb
--- /dev/null
+++ b/2020/day-09/input
@@ -0,0 +1,1000 @@
+1
+15
+32
+16
+6
+20
+25
+30
+38
+31
+48
+47
+19
+23
+39
+50
+41
+4
+27
+12
+21
+24
+26
+43
+2
+3
+5
+7
+8
+9
+6
+72
+10
+20
+11
+13
+14
+30
+25
+23
+15
+16
+17
+18
+19
+22
+21
+12
+32
+24
+28
+26
+27
+35
+29
+31
+33
+34
+36
+37
+38
+42
+39
+30
+40
+43
+41
+47
+46
+44
+50
+49
+45
+75
+51
+53
+57
+56
+81
+59
+83
+70
+64
+72
+67
+91
+69
+71
+73
+84
+85
+92
+89
+90
+93
+96
+94
+98
+123
+104
+120
+154
+115
+126
+141
+133
+131
+157
+139
+287
+238
+209
+144
+158
+175
+185
+179
+182
+183
+187
+190
+192
+286
+289
+264
+257
+241
+256
+259
+466
+270
+275
+283
+324
+462
+302
+323
+331
+333
+362
+361
+372
+365
+370
+377
+524
+475
+497
+498
+521
+844
+500
+515
+529
+545
+553
+558
+585
+1013
+887
+1210
+654
+995
+694
+735
+876
+872
+894
+747
+906
+1060
+972
+1607
+998
+1268
+1247
+1292
+1199
+1074
+1239
+1111
+1768
+1696
+1348
+1389
+1401
+1429
+1611
+1441
+1870
+1619
+1641
+1653
+1745
+1878
+1970
+3279
+2072
+5024
+2273
+2185
+2310
+2313
+3424
+3307
+2459
+3052
+3349
+2737
+2790
+4155
+4732
+4720
+3311
+3623
+4898
+6214
+3398
+3715
+5534
+4042
+4257
+4345
+4458
+4495
+7033
+6618
+4772
+5196
+8673
+6994
+5527
+8940
+9525
+6832
+6934
+8838
+10016
+6709
+7021
+7113
+7440
+14107
+11805
+9238
+16380
+8602
+9230
+8953
+9267
+13639
+14200
+11706
+15536
+13541
+15961
+13766
+21313
+13643
+15859
+13730
+16678
+13822
+14134
+14461
+16042
+16393
+17555
+17832
+17840
+17869
+18183
+29175
+30215
+25126
+45853
+25247
+25349
+27184
+27271
+27373
+33414
+27777
+27465
+27552
+27864
+34576
+32330
+28595
+30503
+43079
+35395
+35387
+35672
+60798
+58540
+43309
+50373
+57588
+50475
+50596
+52518
+55017
+54455
+54838
+54925
+58280
+55242
+70943
+55416
+56459
+125868
+59098
+85983
+73582
+70782
+71059
+85862
+98234
+100969
+172028
+109293
+105891
+101071
+105434
+159351
+125514
+109380
+109697
+109763
+176673
+251382
+156765
+111875
+115557
+144364
+144960
+129880
+141841
+144641
+270262
+223748
+184096
+199203
+202040
+211325
+206505
+250255
+210768
+274244
+219077
+219143
+253744
+340648
+221638
+355132
+227432
+286482
+271721
+245437
+348957
+274840
+366279
+449458
+721179
+383299
+386136
+394864
+996019
+408545
+417273
+605387
+429845
+440715
+505625
+464580
+627130
+576770
+449070
+467075
+472869
+499153
+517158
+520277
+735093
+623797
+660976
+885289
+778163
+791844
+769435
+781000
+803409
+849260
+825818
+990027
+870560
+947003
+948223
+931655
+966228
+916145
+1025840
+1404797
+1090872
+972022
+1486794
+1289712
+2351800
+1464385
+1603981
+1430411
+1547598
+2396858
+1550435
+1673969
+3641512
+1974063
+2115530
+1956255
+1920245
+2495821
+2498658
+1847800
+1882373
+2007017
+1888167
+3735967
+2261734
+3963043
+2402433
+2720123
+4199600
+2894796
+2980846
+3098033
+4217989
+3556342
+4452076
+3224404
+3562136
+3770540
+3730173
+3895184
+3768045
+3802618
+4290600
+3854817
+3889390
+5992829
+8306893
+5690785
+8712952
+7692008
+5122556
+6748891
+6450296
+5875642
+6078879
+9846924
+8346960
+9554965
+16595815
+6786540
+6954577
+9458830
+7498218
+7532791
+13567650
+7570663
+7657435
+7744207
+12529175
+9011946
+10813341
+12077133
+14134502
+14525240
+12865419
+14698784
+11954521
+12325938
+12662182
+13033456
+22890474
+13741117
+20406389
+26211635
+14284758
+14452795
+21951013
+15031009
+15103454
+18384004
+15228098
+15401642
+16756153
+27486251
+15690279
+24988120
+27896428
+52474371
+24280459
+30918377
+24616703
+24987977
+25359394
+25695638
+38392850
+28025875
+42115547
+30134463
+39644152
+29512856
+29483804
+30259107
+30505096
+30629740
+31091921
+69127956
+60113544
+60764203
+39970738
+40306982
+58030891
+48897162
+49268436
+54129559
+49604680
+60575725
+50347371
+56787559
+53721513
+57509679
+98873116
+79860227
+70229845
+80977111
+83642415
+59742911
+80852467
+61134836
+79526902
+97480417
+121159449
+116901103
+80277720
+96758297
+89204144
+140102627
+129128663
+102989949
+99952051
+113464424
+133989786
+111231192
+110509072
+238060552
+153872260
+139603138
+120877747
+129972756
+140020631
+168731046
+141412556
+237778850
+326982994
+196710348
+169481864
+218332807
+228132295
+177036017
+330700134
+189156195
+202942000
+240359855
+210461123
+211183243
+399652348
+456393359
+240481828
+308751677
+549032941
+317056648
+458692662
+358353438
+269993387
+414814867
+345767063
+310894420
+346517881
+458814635
+358638059
+366192212
+628346825
+986700263
+487930437
+399617318
+705155940
+549233505
+421644366
+450942951
+451665071
+510475215
+598835266
+625808325
+578745064
+580887807
+587050035
+615760450
+616511268
+628631446
+962140286
+939241245
+762559491
+712710093
+724830271
+758255377
+1139106661
+1059708720
+909574803
+938873388
+821261684
+873309437
+872587317
+902608022
+961418166
+1030410135
+1089220279
+1337000441
+1194505514
+1202810485
+1299760128
+1203561303
+1232271718
+1341341539
+1353461717
+1919335785
+1487389762
+1437540364
+1470965470
+1483085648
+1693849001
+1694571121
+1848448191
+2958355232
+1723869706
+2173069565
+1745896754
+1775195339
+1991828301
+2164228651
+3613184786
+2283725793
+2406371788
+2397315999
+3183437118
+2557023020
+3262585101
+2573613257
+2694803256
+4311816949
+3462793771
+3994563384
+3228982402
+3165536591
+3176934649
+4860107712
+3418440827
+3469766460
+3521092093
+3715698007
+3737725055
+3767023640
+4058921132
+4447954444
+4561544650
+4681041792
+5574250648
+4803687787
+5659901100
+5130636277
+5251826276
+10463588887
+8803233050
+8597832767
+6342471240
+6394518993
+6405917051
+6647423229
+6583977418
+7185464467
+6888207287
+6939532920
+10401392372
+10340942892
+18999225139
+7504748695
+9426924740
+8506875576
+9251642231
+9242586442
+9484729579
+9934324064
+10055514063
+16807309423
+12989894469
+13334051913
+13053340280
+12736990233
+12748388291
+13579983460
+12800436044
+13231400647
+13472184705
+20170933567
+16372936866
+13827740207
+16191175151
+25675904730
+16756390926
+16011624271
+18441199640
+17749462018
+22483042878
+18494228673
+18727316021
+19419053643
+22734760108
+34452823911
+31527752065
+25485378524
+25548824335
+31464306254
+25537426277
+25979788938
+35483706947
+36476778039
+49213768272
+27299924912
+29839364478
+30018915358
+35197590566
+37221544694
+42305215261
+36243690691
+45850988749
+36190661658
+37168515661
+37913282316
+38146369664
+41462076129
+42153813751
+48220138632
+51022804801
+51034202859
+51086250612
+63201333632
+51517215215
+52837351189
+74103943974
+114235536491
+57318840270
+79375358445
+59858279836
+67932197674
+87337755628
+92516430836
+72434352349
+112017226290
+73359177319
+143550633695
+74337031322
+75081797977
+79608445793
+83615889880
+115566020103
+90373952383
+99242943433
+123951567564
+136927286063
+103923601801
+104354566404
+212009084040
+186354257612
+178027545775
+130678017589
+129753192619
+127790477510
+261643435655
+140366550023
+360886379088
+220127145002
+162808304732
+147696208641
+165455750360
+153945477115
+149418829299
+390036629815
+169982398176
+228306133968
+189616895816
+194297554184
+203166545234
+232145043914
+208278168205
+324481711406
+234107759023
+257543670129
+258468495099
+293486322321
+277449401260
+268157027533
+275486686151
+313151959001
+288062758664
+297115037940
+471323572767
+319401227475
+301641685756
+467097436116
+404090157199
+478653231385
+364279952360
+442385927228
+383914450000
+392783441050
+485727569465
+411444713439
+559185355885
+465821838334
+621042913231
+890097944824
+516012165228
+723491384674
+703315677475
+641729353620
+581308986534
+563549444815
+585177796604
+944475069719
+1426807062149
+788004607199
+871436672435
+945588938894
+1025007194219
+908795606278
+2011984858753
+748194402360
+2477806697087
+776697891050
+804228154489
+1430622028320
+1406110110052
+1047130824868
+981834003562
+1079561610043
+1097321151762
+1101189961832
+1144858431349
+1345045031095
+1148727241419
+1525784056253
+1311743847175
+1675664826924
+1524892293410
+1992719763762
+1619631074795
+2149273185584
+1552422556849
+1580926045539
+1656990008638
+1730028405922
+2493772272514
+1758531894612
+1786062158051
+1851358979357
+2028964828430
+2599553381717
+2446234992927
+2242179583111
+2176882761805
+2697280988198
+3106710101792
+3516090563973
+2460471088594
+3255812462175
+2931374921970
+3470990054152
+4113403347309
+3077314850259
+3172053631644
+3209412565487
+3133348602388
+3282450962771
+3237916054177
+6103428553614
+3488560300534
+5375528185499
+4874163750003
+5618288624571
+4093538562468
+6240058704180
+5173554505081
+4623117754732
+9385879516385
+6169290976147
+9106848925105
+5391846010564
+6959550354686
+5537785938853
+6008689772229
+6210663452647
+8709839570497
+10882853522232
+8856204678748
+9412112335824
+9998645940231
+8864088486033
+12138655641519
+18249968002418
+8716656317200
+7582098863002
+14787640521323
+8967702312471
+9711827187039
+15136993288618
+9796672259813
+10160903693585
+10014963765296
+10929631949417
+11546475711082
+11400535782793
+11602509463211
+11748449391500
+13590788635231
+14718529342726
+14920503023144
+16291938433499
+16298755180202
+16438303541750
+16446187349035
+16549801175473
+24948544214908
+17293926050041
+17378771122815
+17597062628298
+26346473435286
+18679529499510
+41266976458430
+19957575953398
+27894447896710
+19811636025109
+20175867458881
+28194636740535
+22330167732210
+25339238026731
+32737058721952
+23350958854711
+29042375441541
+34035366170048
+31156832884476
+31212441456643
+53233685923441
+43640399485327
+37554638581696
+54240921331996
+61237462113625
+34672697172856
+34890988678339
+38637105452908
+37408698653407
+38491165524619
+38855396958391
+47706083921819
+39769211978507
+45515105485612
+39987503483990
+84390518807917
+65749275322231
+45681126586921
+58241947533050
+61779434163493
+52393334296252
+70981653435150
+89454388989693
+151233823153186
+77396202137397
+72227335754552
+69563685851195
+100416539616401
+72081395826263
+72299687331746
+73163862697475
+73382154202958
+75899864178026
+76264095611798
+77346562483010
+78624608936898
+79756715462497
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-04-25 11:02:12 +0000