111 lines
3.6 KiB
Nim
111 lines
3.6 KiB
Nim
import algorithm, sequtils, strutils
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const
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LeftDigits = [" ## #",
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" ## #",
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" # ##",
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" #### #",
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" # ##",
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" ## #",
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" # ####",
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" ### ##",
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" ## ###",
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" # ##"]
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RightDigits = LeftDigits.mapIt(it.multiReplace(("#", " "), (" ", "#")))
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EndSentinel = "# #"
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MidSentinel = " # # "
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template isEven(n: int): bool = (n and 1) == 0
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proc decodeUPC(input: string) =
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#.................................................................................................
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proc decode(candidate: string): tuple[valid: bool, list: seq[int]] =
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const Invalid = (false, @[])
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var pos = 0
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var next = pos + EndSentinel.len
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if candidate[pos..<next] == EndSentinel:
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pos = next
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else:
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return Invalid
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for _ in 1..6:
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next = pos + 7
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let i = LeftDigits.find(candidate[pos..<next])
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if i >= 0:
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result.list.add i
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pos = next
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else:
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return Invalid
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next = pos + MidSentinel.len
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if candidate[pos..<next] == MidSentinel:
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pos = next
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else:
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return Invalid
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for _ in 1..6:
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next = pos + 7
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let i = RightDigits.find(candidate[pos..<next])
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if i >= 0:
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result.list.add i
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pos = next
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else:
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return Invalid
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next = pos + EndSentinel.len
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if candidate[pos..<next] == EndSentinel:
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pos = next
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else:
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return Invalid
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var sum = 0
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for i, v in result.list:
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sum += (if i.isEven: 3 * v else: v)
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result.valid = sum mod 10 == 0
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#.................................................................................................
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var candidate = input.strip()
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let output = candidate.decode()
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if output.valid:
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echo output.list.join(", ")
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else:
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candidate.reverse()
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let output = candidate.decode()
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if output.valid:
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echo output.list.join(", "), " Upside down"
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elif output.list.len == 0:
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echo "Invalid digit(s)"
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else:
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echo "Invalid checksum: ", output.list.join(", ")
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#———————————————————————————————————————————————————————————————————————————————————————————————————
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when isMainModule:
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const BarCodes = [
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" # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # ",
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" # # # ## ## # #### # # ## # ## # ## # # # ### # ### ## ## ### # # ### ### # # # ",
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" # # # # # ### # # # # # # # # # # ## # ## # ## # ## # # #### ### ## # # ",
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" # # ## ## ## ## # # # # ### # ## ## # # # ## ## # ### ## ## # # #### ## # # # ",
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" # # ### ## # ## ## ### ## # ## # # ## # # ### # ## ## # # ### # ## ## # # # ",
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" # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # ",
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" # # # ## ## # # ## ## # ### ## ## # # # # # # # # ### # # ### # # # # # ",
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" # # # # ## ## # # ## ## ### # # # # # ### ## ## ### ## ### ### ## # ## ### ## # # ",
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" # # ### ## ## # # #### # ## # #### # #### # # # # # ### # # ### # # # ### # # # ",
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" # # # #### ## # #### # # ## ## ### #### # # # # ### # ### ### # # ### # # # ### # # ",
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]
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for barcode in BarCodes:
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barcode.decodeUPC()
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