40 lines
898 B
Kotlin
40 lines
898 B
Kotlin
package be.vandewalleh.aoc.days
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import be.vandewalleh.aoc.utils.input.Day
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import be.vandewalleh.aoc.utils.input.Lines
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@Day(3)
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class Day03(@Lines val input: List<String>) {
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private data class Slope(val x: Int, val y: Int)
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private fun findSlope(slope: Slope): Int {
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val grid = input
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var trees = 0
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var x = 0
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var y = 0
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val width = grid.first().length
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while (y < grid.size - 1) {
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x += slope.x
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y += slope.y
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if (grid[y][x % width] == '#') trees++
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}
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return trees
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}
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fun part1() = findSlope(Slope(x = 3, y = 1))
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fun part2(): Long = listOf(
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Slope(x = 1, y = 1),
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Slope(x = 3, y = 1),
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Slope(x = 5, y = 1),
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Slope(x = 7, y = 1),
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Slope(x = 1, y = 2),
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)
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.map { findSlope(it).toLong() }
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.reduce { acc, trees -> acc * trees }
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}
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