53 lines
1.5 KiB
Text
53 lines
1.5 KiB
Text
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#!/usr/bin/env kotlin
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import java.io.File
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val frequencies = mutableMapOf<Char, MutableList<Pair<Int, Int>>>()
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var gridWidth = 0
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var gridHeight = 0
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File("./input.txt").readLines().also {
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gridHeight = it.size
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}.forEachIndexed { i, line ->
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line.also { gridWidth = it.length }.forEachIndexed chars@{ j, freq ->
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if (freq == '.') return@chars
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val curValue = frequencies.putIfAbsent(
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freq, mutableListOf(Pair(i, j))
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)
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if (curValue !== null) {
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curValue.add(Pair(i, j))
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}
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}
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}
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val antiNodes = hashSetOf<Pair<Int, Int>>()
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frequencies.forEach { (_, points) ->
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points.forEach outer@{ point1 ->
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points.forEach { point2 ->
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if (point1 == point2) return@outer
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val dRow = (point1.first - point2.first)
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val dCol = (point1.second - point2.second)
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val antiNode1 = Pair(point1.first + dRow, point1.second + dCol)
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val antiNode2 = Pair(point2.first - dRow, point2.second - dCol)
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if (
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antiNode1.first >= 0
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&& antiNode1.second >= 0
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&& antiNode1.first < gridHeight
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&& antiNode1.second < gridWidth) {
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antiNodes.add(antiNode1)
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}
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if (
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antiNode2.first >= 0
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&& antiNode2.second >= 0
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&& antiNode2.first < gridHeight
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&& antiNode2.second < gridWidth) {
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antiNodes.add(antiNode2)
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}
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}
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}
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}
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println(antiNodes.size)
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