50 lines
1.5 KiB
Nim
50 lines
1.5 KiB
Nim
import streams, sequtils, pegs, tables, sets, algorithm, strutils
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let parser = peg"""
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grammar <- c ' bags contain ' (nc+ / nob) '.'
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nob <- 'no other bags'
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nc <- {\d} ' ' c ' bag' 's'? ', '?
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c <- {\ident ' ' \ident}
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"""
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let target = "shiny gold"
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iterator asParsed(s: Stream): (string, seq[string]) =
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for l in s.lines:
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if l =~ parser:
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var d = matches.filterIt(it != "").reversed
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let key = d.pop
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yield (key, d)
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proc walkUp(t: TableRef[string, HashSet[string]], tar: string): HashSet[string] =
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if t.contains(tar):
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let parents = t[tar]
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result = parents
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for p in parents:
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result = result + t.walkUp(p)
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proc part1*(s: Stream): int =
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var t = newTable[string, HashSet[string]]()
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for (key, parsed) in s.asParsed:
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var parents = parsed.filterIt(not(it =~ peg"\d+"))
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for p in parents:
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if t.contains(p): t[p].incl(key)
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else: t[p] = [key].toHashSet()
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t.walkUp(target).len
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proc walkDown(t: TableRef[string, TableRef[string, int]], tar: string): int =
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let children = t[tar]
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for (s, n) in children.pairs:
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result += n + (n * t.walkDown(s))
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iterator asPairChunks(s: seq[string]): (string, int) =
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for i in countup(0, s.len - 1, 2): yield (s[i], s[i+1].parseInt)
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proc part2*(s: Stream): int =
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var t = newTable[string, TableRef[string, int]]()
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for (key, parsed) in s.asParsed:
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var innert = newTable[string, int]()
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for (innerkey, n) in parsed.asPairChunks:
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innert[innerkey] = n
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t[key] = innert
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t.walkDown target
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