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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,88 @@ | ||
| import extra | ||
| import gleam/int | ||
| import gleam/list | ||
| import gleam/order | ||
| import gleam/string | ||
|
|
||
| pub type Row { | ||
| Row(result: Int, operands: List(Int)) | ||
| } | ||
|
|
||
| pub fn parse(input: String) -> List(Row) { | ||
| string.split(input, "\n") | ||
| |> list.map(fn(line) { | ||
| case string.split(line, ": ") { | ||
| [result_str, operands_str] -> { | ||
| Row( | ||
| result: extra.yolo_int(result_str), | ||
| operands: string.split(operands_str, " ") | ||
| |> list.map(extra.yolo_int), | ||
| ) | ||
| } | ||
| _ -> panic as "Bad input 1" | ||
| } | ||
| }) | ||
| } | ||
|
|
||
| pub fn pt_1(input: List(Row)) { | ||
| input | ||
| |> list.filter(fn(row) { can_be_combined(row, [int.add, int.multiply]) }) | ||
| |> list.map(fn(row) { row.result }) | ||
| |> int.sum | ||
| } | ||
|
|
||
| pub fn pt_2(input: List(Row)) { | ||
| input | ||
| |> list.filter(fn(row) { | ||
| can_be_combined(row, [int.add, int.multiply, concat_digits]) | ||
| }) | ||
| |> list.map(fn(row) { row.result }) | ||
| |> int.sum | ||
| } | ||
|
|
||
| fn can_be_combined(row: Row, ops: List(fn(Int, Int) -> Int)) -> Bool { | ||
| case row.operands { | ||
| [first, ..rest] -> search(row.result, [#(first, rest)], ops) | ||
| _ -> panic as "No operands?!" | ||
| } | ||
| } | ||
|
|
||
| fn concat_digits(a: Int, b: Int) -> Int { | ||
| // TODO could be faster if we do math (a * log10(b) + b) | ||
| extra.yolo_int(int.to_string(a) <> int.to_string(b)) | ||
| } | ||
|
|
||
| fn search( | ||
| result: Int, | ||
| todos: List(#(Int, List(Int))), | ||
| ops: List(fn(Int, Int) -> Int), | ||
| ) -> Bool { | ||
| case todos { | ||
| [] -> False | ||
| [#(acc_sum, operands), ..rest_of_todos] -> { | ||
| case operands { | ||
| [] -> | ||
| case acc_sum == result { | ||
| True -> True | ||
| False -> search(result, rest_of_todos, ops) | ||
| } | ||
| [operand, ..rest_of_operands] -> { | ||
| case acc_sum > result { | ||
| True -> search(result, rest_of_todos, ops) | ||
| False -> | ||
| search( | ||
| result, | ||
| list.append( | ||
| list.map(ops, fn(op) { | ||
| #(op(acc_sum, operand), rest_of_operands) | ||
| }), | ||
| rest_of_todos, | ||
| ), | ||
| ops, | ||
| ) | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |