31 lines
890 B
Nim
31 lines
890 B
Nim
import streams, bitops, sets
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# TODO: this one needs some refining for sure
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proc row(l: string): uint64 =
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for c in l:
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result = result.rotateLeftBits(1)
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if c == 'B': result.setBit(0)
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proc col(l: string): uint64 =
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for c in l:
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result = result.rotateLeftBits(1)
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if c == 'R': result.setBit(0)
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# do I really need row * 8 + col or can I just keep rotating and shifting
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proc toId(row: uint64, col: uint64): uint64 = (row*8)+col
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proc part1*(s: Stream): int =
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for l in s.lines():
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let id = cast[int](toId(row(l[0 .. 6]), col(l[7 .. ^1])))
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if id > result: result = id
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proc part2*(s: Stream): int =
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var ids = initHashSet[int]()
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for l in s.lines():
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let id = cast[int](toId(row(l[0 .. 6]), col(l[7 .. ^1])))
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ids.incl(id)
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for i in 1..890: # 890 is my answer from part 1
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if ids.contains(i+1) and ids.contains(i-1) and not ids.contains(i):
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return i
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