From 3223fd423344d98261cb1c8189004ed694d8b42a Mon Sep 17 00:00:00 2001
From: Ummon <greg.burri@gmail.com>
Date: Mon, 11 Dec 2017 09:02:45 +0100
Subject: [PATCH] Use of fold instead of custom recursion
---
AdventOfCode2017/Day11.fs | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/AdventOfCode2017/Day11.fs b/AdventOfCode2017/Day11.fs
index 420f9a5..71e9934 100644
--- a/AdventOfCode2017/Day11.fs
+++ b/AdventOfCode2017/Day11.fs
@@ -7,16 +7,18 @@ let distanceInHex (moves : string list) =
let x, y = abs x, abs y
if y >= x then y + (x - y) / 2 else x
- let rec next (x, y) furthest (moves : string list) =
- let furthest' = distance (x, y) |> max furthest
- match moves with
- | "n" :: xs -> next (x, y + 2) furthest' xs
- | "ne" :: xs -> next (x + 1, y + 1) furthest' xs
- | "se" :: xs -> next (x + 1, y - 1) furthest' xs
- | "s" :: xs -> next (x, y - 2) furthest' xs
- | "sw" :: xs -> next (x - 1, y - 1) furthest' xs
- | "nw" :: xs -> next (x - 1, y + 1) furthest' xs
- | _ -> (x, y), furthest'
-
- let destination, furthest = next (0, 0) 0 moves
+ let destination, furthest =
+ moves
+ |> List.fold (
+ fun ((x, y), furthest) m ->
+ let pos =
+ match m with
+ | "n" -> (x , y + 2)
+ | "ne" -> (x + 1, y + 1)
+ | "se" -> (x + 1, y - 1)
+ | "s" -> (x , y - 2)
+ | "sw" -> (x - 1, y - 1)
+ | _ -> (x - 1, y + 1)
+ pos, distance pos |> max furthest
+ ) ((0, 0), 0)
distance destination, furthest
\ No newline at end of file
--
2.49.0