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| -rw-r--r-- | README.md | 6 | ||||
| -rw-r--r-- | src/Day08.kt | 50 |
2 files changed, 53 insertions, 3 deletions
@@ -1,7 +1,7 @@ # Advent of Code 2021 in Kotlin  - - + + Welcome to the Advent of Code[^aoc] Kotlin project created by [tchojnacki][github] using the [Advent of Code Kotlin Template][template] delivered by JetBrains. @@ -15,7 +15,7 @@ Welcome to the Advent of Code[^aoc] Kotlin project created by [tchojnacki][githu | Day 5: Hydrothermal Venture | 🌟 | 🌟 | | Day 6: Lanternfish | 🌟 | 🌟 | | Day 7: The Treachery of Whales | 🌟 | 🌟 | -| Day 8: ??? | | | +| Day 8: Seven Segment Search | 🌟 | 🌟 | | Day 9: ??? | | | | Day 10: ??? | | | | Day 11: ??? | | | diff --git a/src/Day08.kt b/src/Day08.kt new file mode 100644 index 0000000..d0f050e --- /dev/null +++ b/src/Day08.kt @@ -0,0 +1,50 @@ +fun main() { + fun part1(input: List<String>): Int = + input.sumOf { + it + .split("|")[1] + .trim() + .split(" ") + .map(String::length) + .count { len -> len in listOf(2, 3, 4, 7) } + } + + fun part2(input: List<String>): Long = input.sumOf { line -> + val (patternString, outputString) = line.split("|").map(String::trim) + val patterns = patternString.split(" ").map(String::toSet) + + val one = patterns.first { it.size == 2 } + val four = patterns.first { it.size == 4 } + val seven = patterns.first { it.size == 3 } + val eight = patterns.first { it.size == 7 } + + val top = seven - one + val middle = patterns.filter { it.size == 5 }.reduce(Set<Char>::intersect) intersect four + val five = patterns.filter { it.size == 6 }.reduce(Set<Char>::intersect) + middle + val bottom = five - (four + top) + val nine = four + top + bottom + val lowerLeft = eight - nine + val six = five + lowerLeft + val lowerRight = one intersect six + val three = one + top + middle + bottom + val zero = eight - middle + val upperLeft = nine - three + val two = eight - (upperLeft + lowerRight) + + val encodings = listOf(zero, one, two, three, four, five, six, seven, eight, nine) + + outputString + .split(" ") + .joinToString("") { encodings.indexOf(it.toSet()).toString() } + .toLong() + } + + + val testInput = readInputAsLines("Day08_test") + check(part1(testInput) == 26) + check(part2(testInput) == 61229L) + + val input = readInputAsLines("Day08") + println(part1(input)) + println(part2(input)) +} |