24 lines
690 B
Standard ML
24 lines
690 B
Standard ML
|
fun isDecreasing (l: int list) : bool =
|
||
|
|
ListPair.all (fn (a, b) => b < a andalso b >= a - 3) (l, tl l)
|
||
|
|
|
||
|
|
fun isIncreasing (l: int list) : bool =
|
||
|
|
ListPair.all (fn (a, b) => b > a andalso b <= a + 3) (l, tl l)
|
||
|
|
|
||
|
|
val file = TextIO.openIn "day_2.txt"
|
||
|
|
val input = TextIO.inputAll file;
|
||
|
|
TextIO.closeIn file;
|
||
|
|
|
||
|
|
val lines = String.tokens (fn (char) => char = #"\n") input
|
||
|
|
|
||
|
|
val reports = map
|
||
|
|
(fn (line) =>
|
||
|
|
let val numbers = String.tokens Char.isSpace line
|
||
|
|
in map (fn (n) => valOf (Int.fromString n)) numbers end
|
||
|
|
)
|
||
|
|
lines
|
||
|
|
|
||
|
|
val safeReports = List.filter (fn (report) => isDecreasing report orelse isIncreasing report) reports
|
||
|
|
|
||
|
|
val safeAmount = List.length safeReports
|
||
|
|
|