this repo has no description
ft: add day 13
+1058
+966
2021/day13.txt
+966
2021/day13.txt
···
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715
+
470,420
716
+
843,603
717
+
313,78
718
+
711,393
719
+
1139,820
720
+
124,759
721
+
805,610
722
+
85,347
723
+
833,396
724
+
1190,779
725
+
93,366
726
+
1173,100
727
+
495,128
728
+
162,154
729
+
1073,123
730
+
562,639
731
+
291,561
732
+
1151,576
733
+
293,786
734
+
585,590
735
+
1307,738
736
+
1123,827
737
+
661,266
738
+
514,161
739
+
1066,386
740
+
570,894
741
+
725,142
742
+
792,404
743
+
259,478
744
+
36,52
745
+
251,240
746
+
43,432
747
+
190,462
748
+
917,576
749
+
244,4
750
+
259,268
751
+
1141,332
752
+
855,291
753
+
1004,47
754
+
162,68
755
+
502,820
756
+
95,178
757
+
1138,670
758
+
266,326
759
+
666,843
760
+
1084,84
761
+
1051,581
762
+
1220,847
763
+
1027,733
764
+
1153,103
765
+
437,75
766
+
708,299
767
+
1274,346
768
+
264,586
769
+
669,520
770
+
890,191
771
+
247,252
772
+
798,215
773
+
300,19
774
+
166,606
775
+
216,651
776
+
385,267
777
+
248,751
778
+
986,606
779
+
950,147
780
+
468,880
781
+
243,815
782
+
1201,819
783
+
423,110
784
+
939,164
785
+
761,505
786
+
1215,515
787
+
179,429
788
+
1233,374
789
+
551,443
790
+
137,337
791
+
1020,394
792
+
1063,642
793
+
1208,760
794
+
972,499
795
+
922,806
796
+
497,103
797
+
420,705
798
+
92,639
799
+
1081,430
800
+
771,788
801
+
654,225
802
+
751,178
803
+
375,179
804
+
1265,697
805
+
497,743
806
+
331,455
807
+
20,84
808
+
70,817
809
+
1192,450
810
+
835,465
811
+
415,788
812
+
1285,449
813
+
986,135
814
+
699,609
815
+
1222,786
816
+
629,526
817
+
291,512
818
+
1133,172
819
+
924,593
820
+
5,742
821
+
840,287
822
+
893,123
823
+
242,396
824
+
846,462
825
+
410,605
826
+
88,562
827
+
1215,626
828
+
1036,523
829
+
571,367
830
+
1079,885
831
+
425,465
832
+
1158,852
833
+
1218,641
834
+
692,394
835
+
1260,99
836
+
515,291
837
+
990,416
838
+
276,130
839
+
1161,284
840
+
935,226
841
+
843,505
842
+
738,803
843
+
1310,852
844
+
3,738
845
+
288,359
846
+
783,291
847
+
474,756
848
+
689,590
849
+
125,350
850
+
269,259
851
+
102,806
852
+
82,60
853
+
244,803
854
+
977,630
855
+
927,548
856
+
1274,570
857
+
1196,707
858
+
698,563
859
+
115,871
860
+
279,403
861
+
87,231
862
+
1068,74
863
+
652,746
864
+
1057,95
865
+
1282,417
866
+
485,709
867
+
1304,598
868
+
1282,193
869
+
95,515
870
+
647,435
871
+
433,277
872
+
895,106
873
+
70,807
874
+
244,91
875
+
646,838
876
+
748,33
877
+
587,827
878
+
641,480
879
+
1278,299
880
+
1171,301
881
+
1297,268
882
+
50,347
883
+
1089,169
884
+
701,25
885
+
211,338
886
+
1243,379
887
+
13,268
888
+
348,424
889
+
595,733
890
+
616,596
891
+
787,525
892
+
120,779
893
+
423,864
894
+
634,532
895
+
242,844
896
+
873,75
897
+
1267,730
898
+
502,746
899
+
281,173
900
+
822,750
901
+
402,108
902
+
694,701
903
+
206,666
904
+
927,841
905
+
341,816
906
+
594,47
907
+
1067,815
908
+
118,892
909
+
166,807
910
+
95,626
911
+
403,654
912
+
454,100
913
+
59,609
914
+
895,788
915
+
721,241
916
+
676,532
917
+
74,310
918
+
333,485
919
+
1029,84
920
+
830,36
921
+
599,501
922
+
1218,749
923
+
417,123
924
+
1057,123
925
+
694,193
926
+
324,512
927
+
179,494
928
+
842,432
929
+
979,439
930
+
155,479
931
+
1161,610
932
+
187,515
933
+
930,339
934
+
1183,291
935
+
393,318
936
+
1290,532
937
+
788,550
938
+
785,291
939
+
947,830
940
+
1186,759
941
+
867,556
942
+
748,861
943
+
460,177
944
+
713,852
945
+
358,572
946
+
507,633
947
+
1265,421
948
+
631,155
949
+
1243,414
950
+
1222,108
951
+
229,430
952
+
715,285
953
+
818,131
954
+
955
+
fold along x=655
956
+
fold along y=447
957
+
fold along x=327
958
+
fold along y=223
959
+
fold along x=163
960
+
fold along y=111
961
+
fold along x=81
962
+
fold along y=55
963
+
fold along x=40
964
+
fold along y=27
965
+
fold along y=13
966
+
fold along y=6
+92
2021/solutions.livemd
+92
2021/solutions.livemd
···
1067
1067
```output
1068
1068
98441
1069
1069
```
1070
+
1071
+
## Day 13
1072
+
1073
+
```elixir
1074
+
[input, folds] =
1075
+
File.read!("day13.txt")
1076
+
|> String.trim()
1077
+
|> String.split("\n\n")
1078
+
1079
+
input =
1080
+
input
1081
+
|> String.split("\n")
1082
+
|> Enum.map(fn line ->
1083
+
[x, y] = String.split(line, ",")
1084
+
1085
+
{String.to_integer(x), String.to_integer(y)}
1086
+
end)
1087
+
|> MapSet.new()
1088
+
1089
+
folds =
1090
+
folds
1091
+
|> String.split("\n")
1092
+
|> Enum.map(fn
1093
+
"fold along " <> <<c>> <> "=" <> rest ->
1094
+
{String.to_atom(<<c>>), String.to_integer(rest)}
1095
+
end)
1096
+
1097
+
defmodule Day13 do
1098
+
def fold({orientation, pos}, set) do
1099
+
Enum.reduce(set, MapSet.new(), fn point, acc ->
1100
+
new_point = folded_coords(orientation, pos, point)
1101
+
1102
+
MapSet.put(acc, new_point)
1103
+
end)
1104
+
end
1105
+
1106
+
defp folded_coords(:x, col, {x, y}) when x > col, do: {abs(2 * col - x), y}
1107
+
defp folded_coords(:y, row, {x, y}) when y > row, do: {x, abs(2 * row - y)}
1108
+
defp folded_coords(_, _, point), do: point
1109
+
1110
+
def draw(set) do
1111
+
set
1112
+
|> Enum.group_by(&elem(&1, 1))
1113
+
|> Enum.sort()
1114
+
|> Enum.map(fn {_, points} ->
1115
+
points
1116
+
|> Enum.map(&elem(&1, 0))
1117
+
|> Enum.sort()
1118
+
|> Enum.chunk_every(2, 1)
1119
+
|> Enum.map(fn
1120
+
[a, b] -> b - a
1121
+
_ -> 0
1122
+
end)
1123
+
|> Enum.map(&String.pad_trailing("█", &1, " "))
1124
+
end)
1125
+
|> Enum.join("\n")
1126
+
end
1127
+
end
1128
+
```
1129
+
1130
+
```output
1131
+
{:module, Day13, <<70, 79, 82, 49, 0, 0, 13, ...>>, {:draw, 1}}
1132
+
```
1133
+
1134
+
```elixir
1135
+
Day13.fold(hd(folds), input) |> MapSet.size()
1136
+
```
1137
+
1138
+
```output
1139
+
802
1140
+
```
1141
+
1142
+
```elixir
1143
+
Enum.reduce(folds, input, &Day13.fold/2)
1144
+
|> Day13.draw()
1145
+
|> IO.puts()
1146
+
```
1147
+
1148
+
```output
1149
+
███ █ █ █ █ ████ ████ ██ █ █ ███
1150
+
█ █ █ █ █ █ █ █ █ █ █ █ █ █
1151
+
█ █ ██ ████ ███ █ █ █ █ ███
1152
+
███ █ █ █ █ █ █ █ ██ █ █ █ █
1153
+
█ █ █ █ █ █ █ █ █ █ █ █ █ █
1154
+
█ █ █ █ █ █ █ ████ ███ ██ ███
1155
+
```
1156
+
1157
+
```output
1158
+
:ok
1159
+
```
1160
+
1161
+
## Day 14