55 lines
1.7 KiB
Kotlin
55 lines
1.7 KiB
Kotlin
package aoc2023
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import println
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import readInput
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import splitInts
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/*
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--- Day 6: Wait For It ---
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https://adventofcode.com/2023/day/6
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*/
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fun main() {
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val inlineTestInput = """
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Time: 7 15 30
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Distance: 9 40 200
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"""
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// Next time, don't be stupid. This is not the right formula for the problem:
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// distance = (bt * (bt+1))/2 + bt * (tt - 2 * bt)
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// Spend 30 minutes figuring out why I don't win any race when the boat is actually accelerating!
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fun part1(input: List<String>): Int {
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val times = input[0].split(":")[1].splitInts()
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val distances = input[1].split(":")[1].splitInts()
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val result = times.withIndex().map { (i, tt) ->
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IntRange(1, tt - 1).count {
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it * (tt - it) > distances[i]
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}
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}
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return result.reduce { acc, i -> acc * i }
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}
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fun part2(input: List<String>): Int {
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val tt = input[0].split(":")[1].replace(" ", "").toLong()
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val distance = input[1].split(":")[1].replace(" ", "").toLong()
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val result = LongRange(1, tt - 1).count {
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it * (tt - it) > distance
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}
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return result
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}
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// test if implementation meets criteria from the description, like:
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val testInput = inlineTestInput.trim().reader().readLines()
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//val testInput = readInput("aoc2023/Day06_test")
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val testInputPart1Result = part1(testInput)
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println("Part 1 Test: $testInputPart1Result")
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val testInputPart2Result = part2(testInput)
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println("Part 2 Test: $testInputPart2Result")
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check(testInputPart1Result == 288)
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check(testInputPart2Result == 71503)
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val input = readInput("aoc2023/Day06")
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part1(input).println()
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part2(input).println()
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}
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