Day 14 part 1

2021/nim/day14.nim

@@ -0,0 +1,48 @@
+import ./common, std/[sequtils, algorithm, sugar, sets, strformat, strutils, tables]
+
+proc parse(input: Lines): (string, Table[(char, char), char]) =
+  result[0] = input[0]
+  for i in 2..<input.len():
+    var c = input[i].split(" -> ")
+    result[1][(c[0][0], c[0][1])] = c[1][0]
+
+proc stepPolymer(polymer: string, combis: Table[(char, char), char]): string =
+  result.add polymer[0]
+  var i = 1
+  while i < polymer.len:
+    var key = (polymer[i-1], polymer[i])
+    if combis.contains key: result.add combis[key]
+    result.add polymer[i]
+    i += 1
+
+proc p1(input: Lines): int =
+  var (polymer, combis) = input.parse
+  for i in 1..10:
+    polymer = polymer.stepPolymer combis
+  var pps = polymer.toCountTable.values.toSeq
+  max(pps) - min(pps)
+
+proc p2(input: Lines): int =
+  return 0
+
+const input = """
+NNCB
+
+CH -> B
+HH -> N
+CB -> H
+NH -> C
+HB -> C
+HC -> B
+HN -> C
+NN -> C
+BH -> H
+NC -> B
+NB -> B
+BN -> B
+BB -> N
+BC -> B
+CC -> N
+CN -> C
+""".strip().split('\n').mapIt(it.strip)
+doDay 14, n => n.loadInput, p1, p2, (input, 1588, 0)