79 lines
2.7 KiB
Nim
79 lines
2.7 KiB
Nim
import std/[strutils, sequtils, options, math, parseutils]
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import ./common
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const ASCII_ZERO = int('0')
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type BitCounter = object
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zeroes: int
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ones: int
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proc countBits(inputs: seq[string], maybeWidth: Option[int], offset = 0): seq[BitCounter] =
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let width = maybeWidth.get(inputs[0].len())
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let maxIndex = offset+width
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for i in offset..<maxIndex: result.add(BitCounter(zeroes: 0, ones: 0))
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for binstring in inputs:
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for i in offset..<maxIndex:
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let outIndex = i - offset
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if (binstring[i].int() - ASCII_ZERO) > 0: inc result[outIndex].ones
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else: inc result[outIndex].zeroes
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proc powerConsumption(inputs: seq[string]): int =
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let counters = inputs.countBits(none(int))
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let width: Natural = inputs[0].len()
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for i in 0..<width:
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if counters[i].ones > counters[i].zeroes: inc result
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result = result shl 1
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result = result shr 1
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result = result * (result xor ((2 ^ width) - 1))
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proc lifeSupportRating(inputs: seq[string]): int =
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let width: Natural = inputs[0].len()
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var oxygenRating, co2Rating = 0
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var oxygenCandidates, co2Candidates: seq[int] = toSeq(0..<inputs.len)
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for i in 0..<width:
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var newOxygenCandidates, newCo2Candidates: seq[int] = @[]
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if oxygenRating == 0:
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let candidates = oxygenCandidates.mapIt(inputs[it])
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let counters = countBits(candidates, some(1), i)
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let moreCommon: char = if counters[0].ones >= counters[0].zeroes: '1' else: '0'
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for j in oxygenCandidates:
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if inputs[j][i] == moreCommon:
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newOxygenCandidates.add(j)
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if newOxygenCandidates.len() == 1:
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discard inputs[newOxygenCandidates[0]].parseBin(oxygenRating)
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if co2Rating == 0:
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let candidates = co2Candidates.mapIt(inputs[it])
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let counters = countBits(candidates, some(1), i)
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let lessCommon: char = if counters[0].zeroes <= counters[0].ones: '0' else: '1'
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for j in co2Candidates:
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if inputs[j][i] == lessCommon:
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newCo2Candidates.add(j)
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if newCo2Candidates.len() == 1:
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discard inputs[newCo2Candidates[0]].parseBin(co2Rating)
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oxygenCandidates = newOxygenCandidates
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co2Candidates = newCo2Candidates
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if oxygenRating != 0 and co2Rating != 0: break
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return oxygenRating * co2Rating
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let input = 3.loadInput()
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time("powerConsumption part 1"): echo input.powerConsumption()
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time("lifeSupportRating part 2"): echo input.lifeSupportRating()
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when not defined(release):
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static:
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let testInput = @[
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"00100",
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"11110",
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"10110",
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"10111",
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"10101",
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"01111",
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"00111",
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"11100",
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"10000",
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"11001",
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"00010",
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"01010",
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]
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doAssert testInput.powerConsumption() == 198
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doAssert testInput.lifeSupportRating() == 230
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