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3
       
-
       
# Untitled notebook

     

       
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5
       
 
       
```elixir

     

       
6
       
 
       
Mix.install([:kino_aoc, :arrays])

     
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4432

     

       
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```

     

       
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# Day 06

     

       
4
       
 
       


     

       
5
       
 
       
```elixir

     

       
6
       
 
       
Mix.install([:kino_aoc, :arrays])

     
···

       
184
       
 
       
4432

     

       
185
       
 
       
```

     

       
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···

       
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56
       
 
       
```

     

       
57
       
 
       
warning: code block contains unused literal "190: 10 19\n3267: 81 40 27\n83: 17 5\n156: 15 6\n7290: 6 8 6 15\n161011: 16 10 13\n192: 17 8 14\n21037: 9 7 18 13\n292: 11 6 16 20\n" (remove the literal or assign it to _ to avoid warnings)

     

       
58
       
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└─ Workspace/hauleth/advent-of-code/2024/day07.livemd#cell:5stfqvjgwz4d5v5a:1

     

       
59
       
 
       


     

       
60
       
 
       
```

     

       
61
       
 
       


     
···

       
123
       
 
       
defmodule Eq.P1 do

     

       
124
       
 
       
  def possible?(0, []), do: true

     

       
125
       
 
       
  def possible?(a, [a]), do: true

     

       
126
       
-
       
  def possible?(0, [_|_]), do: false

     

       
127
       
 
       
  def possible?(_, []), do: false

     

       
128
       
 
       
  def possible?(a, _) when a < 0, do: false

     

       
129
       
 
       


     
···

       
146
       
 
       
|> Enum.filter(fn {target, vals} ->

     

       
147
       
 
       
  Eq.P1.possible?(target, Enum.reverse(vals))

     

       
148
       
 
       
end)

     

       
149
       
-
       
|> Enum.reduce(0, & elem(&1, 0) + &2)

     

       
150
       
 
       
```

     

       
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···

       
161
       
 
       
defmodule Eq.P2 do

     

       
162
       
 
       
  def possible?(a, [hd | rest]), do: possible?(a, hd, rest)

     

       
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164
       
-
       
  def possible?(a, a, []), do: true

     

       
165
       
-
       
  def possible?(_, _, []), do: false

     

       
166
       
-
       
  def possible?(a, b, _) when b > a, do: false

     

       
167
       
 
       


     

       
168
       
-
       
  def possible?(target, curr, [a | rest]) do

     

       
169
       
 
       
    possible?(target, concat(curr, a), rest) or

     

       
170
       
-
       
      possible?(target, curr + a, rest) or

     

       
171
       
-
       
      possible?(target, curr * a, rest)

     

       
172
       
 
       
  end

     

       
173
       
 
       


     

       
174
       
-
       
  def concat(a, b) do

     

       
175
       
-
       
    String.to_integer("#{a}#{b}")

     

       
176
       
-
       
  end

     

       
0
       
 
       

     

       
0
       
 
       

     

       
177
       
 
       
end

     

       
178
       
 
       
```

     

       
179
       
 
       


     

       
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182
       
 
       
```

     

       
183
       
-
       
{:module, Eq.P2, <<70, 79, 82, 49, 0, 0, 10, ...>>, {:concat, 2}}

     

       
184
       
 
       
```

     

       
185
       
 
       


     

       
186
       
 
       
```elixir

     
···

       
200
       
 
       
264184041398847

     

       
201
       
 
       
```

     

       
202
       
 
       


     

       
203
       
-
       
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···

       
55
       
 
       


     

       
56
       
 
       
```

     

       
57
       
 
       
warning: code block contains unused literal "190: 10 19\n3267: 81 40 27\n83: 17 5\n156: 15 6\n7290: 6 8 6 15\n161011: 16 10 13\n192: 17 8 14\n21037: 9 7 18 13\n292: 11 6 16 20\n" (remove the literal or assign it to _ to avoid warnings)

     

       
58
       
+
       
└─ Workspace/hauleth/advent-of-code/2024/day07.livemd#cell:7pxlqq2wa3oqdwfr:1

     

       
59
       
 
       


     

       
60
       
 
       
```

     

       
61
       
 
       


     
···

       
123
       
 
       
defmodule Eq.P1 do

     

       
124
       
 
       
  def possible?(0, []), do: true

     

       
125
       
 
       
  def possible?(a, [a]), do: true

     

       
126
       
+
       
  def possible?(0, [_ | _]), do: false

     

       
127
       
 
       
  def possible?(_, []), do: false

     

       
128
       
 
       
  def possible?(a, _) when a < 0, do: false

     

       
129
       
 
       


     
···

       
146
       
 
       
|> Enum.filter(fn {target, vals} ->

     

       
147
       
 
       
  Eq.P1.possible?(target, Enum.reverse(vals))

     

       
148
       
 
       
end)

     

       
149
       
+
       
|> Enum.reduce(0, &(elem(&1, 0) + &2))

     

       
150
       
 
       
```

     

       
151
       
 
       


     

       
152
       
 
       
<!-- livebook:{"output":true} -->

     
···

       
161
       
 
       
defmodule Eq.P2 do

     

       
162
       
 
       
  def possible?(a, [hd | rest]), do: possible?(a, hd, rest)

     

       
163
       
 
       


     

       
164
       
+
       
  defp possible?(a, a, []), do: true

     

       
165
       
+
       
  defp possible?(_, _, []), do: false

     

       
166
       
+
       
  defp possible?(a, b, _) when b > a, do: false

     

       
167
       
 
       


     

       
168
       
+
       
  defp possible?(target, curr, [a | rest]) do

     

       
169
       
 
       
    possible?(target, concat(curr, a), rest) or

     

       
170
       
+
       
      possible?(target, curr * a, rest) or

     

       
171
       
+
       
      possible?(target, curr + a, rest)

     

       
172
       
 
       
  end

     

       
173
       
 
       


     

       
174
       
+
       
  defp concat(a, b), do: a * l10(b) + b

     

       
175
       
+
       


     

       
176
       
+
       
  defp l10(n) when n >= 100, do: 1000

     

       
177
       
+
       
  defp l10(n) when n >= 10, do: 100

     

       
178
       
+
       
  defp l10(_), do: 10

     

       
179
       
 
       
end

     

       
180
       
 
       
```

     

       
181
       
 
       


     

       
182
       
 
       
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184
       
 
       
```

     

       
185
       
+
       
{:module, Eq.P2, <<70, 79, 82, 49, 0, 0, 9, ...>>, {:l10, 1}}

     

       
186
       
 
       
```

     

       
187
       
 
       


     

       
188
       
 
       
```elixir

     
···

       
202
       
 
       
264184041398847

     

       
203
       
 
       
```

     

       
204
       
 
       


     

       
205
       
+
       
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