hauleth.dev
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2024 day 08
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2024/day08.livemd
+327
2024/day08.livemd
···
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<!-- livebook:{"persist_outputs":true} -->
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# Day 08
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```elixir
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Mix.install([:kino_aoc])
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```
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## Section
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<!-- livebook:{"attrs":"eyJhc3NpZ25fdG8iOiJwdXp6bGVfaW5wdXQiLCJkYXkiOiI4Iiwic2Vzc2lvbl9zZWNyZXQiOiJBRFZFTlRfT0ZfQ09ERV9TRVNTSU9OIiwieWVhciI6IjIwMjQifQ","chunks":null,"kind":"Elixir.KinoAOC.HelperCell","livebook_object":"smart_cell"} -->
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```elixir
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{:ok, puzzle_input} =
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KinoAOC.download_puzzle("2024", "8", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))
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```
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<!-- livebook:{"output":true} -->
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```
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{:ok,
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"..........M..........j.............y.....O........\n...B...............q......m........lGO............\n....................q......2.l.GQ...O.............\n.....X.......................................4....\n.....................q............................\n....M......P...............xl.K.............2.....\n....F.........L.......C.K..............m..........\n..........FM......P....jy......m..........o...r...\n..X.......P.....RL..............G..x..........4...\n............L..........NC.....q...................\n.....C.X...............K....y..........4..........\n........S...R.............j.x.....V...4...........\n.....................R..x.....V..i......m.........\n...........................R.V......N.......X.....\n.....F.........M......N......E....................\n................v................T.......F......O.\n.............................N...V.......Q........\n...v.....................C.....i..................\n......c.....W..n.w........................E.......\n3...................c.....................Q..6....\n...........h......................j...............\n.......n.0......h.................E..............2\n.v.............7.......120.....c..................\n......n.0............w...........D.t.........E...r\n....8..3......0.w.hP....z...D..T...............r..\n.................f........T........G......eQ......\n......f.n.....7..p................................\n.....Y..7.......f......I......D......K............\n............Uf....T..W.....D..r...i...............\n......I...............................Z...........\n....5....B.......b..............s..............Z..\n..........d...W..Uwh.............c..........i.....\n..I.3..Y......................e...................\n.....p.b..........k......7........................\np...........k....I..b..........s..................\n.....k.......o...........W........................\n.A..Y..........U.................a........6.......\n..A...Y.p...................................6.....\nB......k..........................Z............u..\n...3.....................s..............a.........\n......A.........................g.....a...........\n.......A....8...b.U......H....sS..................\n.........................S1.............t.........\n.....................9z..e.....5..1.g.u...........\n.......................z....d....g....H.J....o.6..\n........B................d.....u....9.J.H.........\n.8........S.................u9.............J.....H\n.....................Z5.............t1...........a\n.....................e..v...................o..t..\n.....8...............L.....z.............J........"}
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```
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```elixir
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# puzzle_input =
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"""
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............
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........0...
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.....0......
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.......0....
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....0.......
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......A.....
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............
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............
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........A...
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.........A..
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............
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............
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"""
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freqs =
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puzzle_input
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|> String.split("\n", trim: true)
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|> Enum.with_index()
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|> Enum.flat_map(fn {row, y} ->
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row
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|> String.to_charlist()
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|> Enum.with_index()
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|> Enum.filter(fn {freq, _} -> freq != ?. end)
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|> Enum.map(fn {freq, x} -> {{x, y}, freq} end)
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end)
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|> Map.new()
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|> Enum.group_by(&elem(&1, 1), &elem(&1, 0))
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```
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<!-- livebook:{"output":true} -->
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```
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warning: code block contains unused literal "............\n........0...\n.....0......\n.......0....\n....0.......\n......A.....\n............\n............\n........A...\n.........A..\n............\n............\n" (remove the literal or assign it to _ to avoid warnings)
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└─ Workspace/hauleth/advent-of-code/2024/day08.livemd#cell:y5uv5vxll4fey6gh:1
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```
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<!-- livebook:{"output":true} -->
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```
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%{
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117 => [{28, 46}, {31, 45}, {38, 43}, {47, 38}],
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73 => [{2, 32}, {17, 34}, {23, 27}, {6, 29}],
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89 => [{4, 36}, {7, 32}, {6, 37}, {5, 27}],
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48 => [{25, 22}, {9, 21}, {8, 23}, {14, 24}],
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57 => [{29, 46}, {21, 43}, {36, 45}],
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113 => [{30, 9}, {20, 2}, {21, 4}, {19, 1}],
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69 => [{42, 18}, {34, 21}, {45, 23}, {29, 14}],
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88 => [{7, 10}, {5, 3}, {44, 13}, {2, 8}],
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100 => [{25, 45}, {28, 44}, {10, 31}],
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71 => [{36, 1}, {35, 25}, {31, 2}, {32, 8}],
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98 => [{16, 41}, {7, 33}, {20, 34}, {17, 30}],
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81 => [{42, 19}, {41, 16}, {43, 25}, {32, 2}],
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76 => [{12, 9}, {14, 6}, {17, 8}, {21, 49}],
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85 => [{15, 36}, {12, 28}, {17, 31}, {18, 41}],
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120 => [{27, 5}, {35, 8}, {28, 11}, {24, 12}],
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109 => [{26, 1}, {39, 6}, {40, 12}, {31, 7}],
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72 => [{38, 44}, {40, 45}, {49, 46}, {25, 41}],
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110 => [{8, 26}, {7, 21}, {15, 18}, {6, 23}],
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68 => [{30, 27}, {28, 24}, {27, 28}, {33, 23}],
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86 => [{29, 13}, {33, 16}, {30, 12}, {34, 11}],
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116 => [{35, 23}, {36, 47}, {47, 48}, {40, 42}],
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51 => [{7, 24}, {0, 19}, {3, 39}, {4, 32}],
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80 => [{18, 7}, {19, 24}, {10, 8}, {11, 5}],
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77 => [{11, 7}, {15, 14}, {10, 0}, {4, 5}],
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78 => [{22, 14}, {29, 16}, {36, 13}, {23, 9}],
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108 => [{29, 2}, {28, 5}, {35, 1}],
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103 => [{32, 40}, {36, 43}, {33, 44}],
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122 => [{27, 49}, {23, 44}, {24, 24}, {22, 43}],
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83 => [{10, 46}, {25, 42}, {31, 41}, {8, 11}],
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74 => [{38, 45}, {41, 49}, {43, 46}, {40, 44}],
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99 => [{31, 22}, {33, 31}, {20, 19}, {6, 18}],
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112 => [{5, 33}, {17, 26}, {8, 37}, {0, 34}],
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97 => [{38, 40}, {33, 36}, {49, 47}, {40, 39}],
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104 => [{16, 21}, {19, 31}, {11, 20}, {18, 24}],
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75 => [{30, 5}, {24, 6}, {23, 10}, {37, 27}],
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90 => [{21, 47}, {47, 30}, {34, 38}, {38, 29}],
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55 => [{15, 22}, {14, 26}, {8, 27}, {25, 33}],
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52 => [{45, 3}, {38, 11}, {39, 10}, {46, 8}],
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111 => [{13, 35}, {42, 7}, {45, 44}, {44, 48}],
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87 => [{25, 35}, {12, 18}, {14, 31}, {21, 28}],
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119 => [{21, 23}, {18, 31}, {17, 18}, {16, 24}],
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82 => [{12, 11}, {27, 13}, {21, 12}, {16, 8}],
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53 => [{22, 47}, {31, 43}, {4, 30}],
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50 => [{27, 2}, {24, 22}, {44, 5}, {49, 21}],
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66 => [{8, 45}, {9, 30}, {3, 1}, {0, ...}],
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70 => [{5, 14}, {41, 15}, {10, ...}, {...}],
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56 => [{12, 41}, {4, ...}, {...}, ...],
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102 => [{17, ...}, {...}, ...],
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105 => [{...}, ...],
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121 => [...],
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...
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}
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```
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```elixir
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{w, h} =
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puzzle_input
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|> String.split("\n", trim: true)
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|> then(fn [a | _] = lst ->
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{byte_size(a), length(lst)}
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end)
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```
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<!-- livebook:{"output":true} -->
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```
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{50, 50}
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```
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```elixir
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defmodule Antennas do
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def each_pair([]), do: []
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def each_pair([a | rest]) do
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for(b <- rest, do: {a, b}) ++ each_pair(rest)
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end
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def antinodes({xa, ya}, {xb, yb}) do
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dx = xa - xb
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dy = ya - yb
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Stream.from_index()
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|> Stream.flat_map(fn n ->
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dx = dx * n
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dy = dy * n
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[{xa + dx, ya + dy}, {xb - dx, yb - dy}]
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end)
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end
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end
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```
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<!-- livebook:{"output":true} -->
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```
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{:module, Antennas, <<70, 79, 82, 49, 0, 0, 10, ...>>, {:antinodes, 2}}
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```
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## Part 1
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```elixir
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antinodes =
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for {_, antennas} <- freqs,
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{a, b} <- Antennas.each_pair(antennas),
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{x, y} = node <- Antennas.antinodes(a, b) |> Stream.drop(2) |> Enum.take(2),
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x in 0..(w - 1) and y in 0..(h - 1),
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into: MapSet.new() do
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node
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end
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```
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<!-- livebook:{"output":true} -->
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```
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MapSet.new([
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{20, 41},
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{20, 3},
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{16, 10},
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{26, 21},
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{6, 18},
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{10, 32},
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{20, 30},
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{33, 17},
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{17, 30},
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{29, 28},
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{40, 35},
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{28, 37},
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{25, 49},
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{10, 19},
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{14, 17},
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{35, 7},
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{29, 48},
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{1, 34},
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{23, 8},
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{35, 6},
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{49, 17},
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{46, 38},
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{5, 39},
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{37, 29},
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{16, 15},
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{48, 41},
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{4, 18},
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{24, 15},
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{33, 44},
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{39, 18},
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{40, 25},
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{35, 21},
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{41, 17},
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{20, 37},
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{45, 24},
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{0, 35},
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{18, 3},
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{1, 36},
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{35, 41},
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{37, 28},
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{28, 15},
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{29, 38},
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{46, 43},
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{31, 19},
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{19, 39},
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{43, 10},
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{38, 10},
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{21, 26},
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{28, ...},
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{...},
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...
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])
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```
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```elixir
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MapSet.size(antinodes)
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```
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<!-- livebook:{"output":true} -->
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```
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398
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```
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## Part 2
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```elixir
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antinodes_res =
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for {_, antennas} <- freqs,
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{a, b} <- Antennas.each_pair(antennas),
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{x, y} = node <- Enum.take(Antennas.antinodes(a, b), 100),
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x in 0..(w - 1) and y in 0..(h - 1),
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into: MapSet.new() do
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node
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end
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```
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<!-- livebook:{"output":true} -->
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```
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MapSet.new([
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{37, 47},
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{35, 30},
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{4, 5},
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{20, 41},
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{31, 42},
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{9, 34},
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{47, 38},
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{20, 3},
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{47, 44},
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{22, 36},
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{45, 7},
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{19, 38},
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{27, 21},
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{9, 33},
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{16, 10},
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{21, 45},
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{26, 21},
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{21, 48},
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{16, 38},
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{35, 26},
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{28, 20},
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{45, 19},
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{27, 22},
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{16, 24},
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{6, 18},
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{10, 32},
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{33, 15},
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{36, 14},
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{20, 30},
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{33, 17},
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{41, 1},
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{36, 25},
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{28, 48},
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{5, 9},
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{14, 16},
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{17, 30},
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{30, 49},
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{32, 18},
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{29, 28},
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{40, 35},
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{6, 23},
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{17, 39},
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{28, 37},
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{6, 29},
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{39, 23},
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{49, 16},
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{34, 0},
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{11, 37},
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{25, ...},
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{...},
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...
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])
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```
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```elixir
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MapSet.size(antinodes_res)
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```
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<!-- livebook:{"output":true} -->
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```
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1333
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```
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<!-- livebook:{"offset":9159,"stamp":{"token":"XCP.vUy-wiQ1Ola4DEyyjRWCHAhmtmjmoDVd4jyZ0g5rhe0RM8-OKii82hOqtdVQ6B_yetZ17Z8avgol_Frq-whc91b45zMSMIRVIC-azF_IQmYLdHX0p3LEQ0xKLcBUuir19OQ","version":2}} -->