From 83eafe403ec45d4b9eb8b777cabb60ea9a8efca3 Mon Sep 17 00:00:00 2001
From: Daniel Flanagan <daniel@lyte.dev>
Date: Fri, 11 Dec 2020 23:29:49 -0600
Subject: [PATCH] Part 1 day 12

---
 2020/src/day12.nim | 26 ++++++++++++++++++++++----
 2020/src/day8.nim  |  2 +-
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/2020/src/day12.nim b/2020/src/day12.nim
index da5606d..5e5f346 100644
--- a/2020/src/day12.nim
+++ b/2020/src/day12.nim
@@ -1,13 +1,31 @@
-import streams, sequtils
+import streams, sequtils, strutils, tables
 
 type Dir = enum north, east, south, west
 
-proc left(
+proc left(d: Dir, n = 1): Dir = Dir((ord(d) - n) %% 4)
+proc right(d: Dir, n = 1): Dir = Dir((ord(d) + n) %% 4)
+
+const dirMap = {north: (0, -1), east: (1, 0), south: (0, 1), west: (-1, 0)}.toTable
+
+proc move(pos: (int, int), nvel: (int, int), mag: int): (int, int) =
+  ((pos[0] + (nvel[0] * mag)), (pos[1] + (nvel[1] * mag)))
 
 proc part1*(s: Stream): int =
+  var d = east
+  var p = (0, 0)
   for l in s.lines:
-    echo l
-  9
+    let arg = l[1..^1].parseInt
+    echo arg
+    case l[0]:
+      of 'N': p = p.move(dirMap[north], arg)
+      of 'S': p = p.move(dirMap[south], arg)
+      of 'E': p = p.move(dirMap[east], arg)
+      of 'W': p = p.move(dirMap[west], arg)
+      of 'L': d = d.left(arg div 90)
+      of 'R': d = d.right(arg div 90)
+      else: p = p.move(dirMap[d], arg)
+  p[0].abs + p[1].abs
+
 
 proc part2*(s: Stream): int =
   9
diff --git a/2020/src/day8.nim b/2020/src/day8.nim
index da3eb4b..ae5a31b 100644
--- a/2020/src/day8.nim
+++ b/2020/src/day8.nim
@@ -54,7 +54,7 @@ proc flipped(h: var HandheldState): HandheldState =
 proc altHandheld(h: var HandheldState): Option[HandheldState] =
   case h.bootcode[h.pointer].instruction:
     of acc: return none(HandheldState)
-    of jmp, nop: some(h.flipped)
+    of jmp, nop: return some(h.flipped)
 
 proc part2*(s: Stream): int =
   var alts = initTable[int, HandheldState]()