From 63882ceb0448ed13f9c2b673dd87c617351b538d Mon Sep 17 00:00:00 2001
From: Daniel Flanagan <daniel@lyte.dev>
Date: Mon, 13 Dec 2021 11:46:55 -0600
Subject: [PATCH] Day 12 part 1

---
 2021/nim/day12.nim | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 2021/nim/day12.nim

diff --git a/2021/nim/day12.nim b/2021/nim/day12.nim
new file mode 100644
index 0000000..e22b5df
--- /dev/null
+++ b/2021/nim/day12.nim
@@ -0,0 +1,43 @@
+import ./common, std/[sequtils, algorithm, sugar, sets, strformat, strutils, tables]
+
+proc visit(curNode: string, graph: Table[string, HashSet[string]], visitedNodes: HashSet[string]): int =
+  if curNode == "end": return 1
+  let nv = if curNode == curNode.toUpper(): visitedNodes else: visitedNodes + [curNode].toHashSet
+  let toVisit = (graph[curNode] - nv)
+  if toVisit.len() == 0: return 0
+  for node in toVisit: result += visit(node, graph, nv)
+
+proc pathing(input: seq[string]): int =
+  var graph: Table[string, HashSet[string]] = initTable[string, HashSet[string]]()
+  for l in input:
+    let nodes = l.split("-")
+    if graph.hasKey(nodes[0]): graph[nodes[0]].incl(nodes[1])
+    else: graph[nodes[0]] = toHashSet([nodes[1]])
+    if graph.hasKey(nodes[1]): graph[nodes[1]].incl(nodes[0])
+    else: graph[nodes[1]] = toHashSet([nodes[0]])
+  visit("start", graph, toHashSet[string]([]))
+
+proc part2(input: seq[string]): int = 
+  result = 0
+
+doDay 12, n => n.loadInput, pathing, part2,
+  @[
+    "fs-end",
+    "he-DX",
+    "fs-he",
+    "start-DX",
+    "pj-DX",
+    "end-zg",
+    "zg-sl",
+    "zg-pj",
+    "pj-he",
+    "RW-he",
+    "fs-DX",
+    "pj-RW",
+    "zg-RW",
+    "start-pj",
+    "he-WI",
+    "zg-he",
+    "pj-fs",
+    "start-RW",
+    ], 226, 0