Day 8

day08.kts

@@ -0,0 +1,82 @@
+#!/usr/bin/env kotlin
+import java.util.Scanner
+
+val scanner = Scanner(System.`in`)
+
+val antennaMap = mutableMapOf<String, MutableList<Pair<Int, Int>>>()
+val antinodeSet = mutableSetOf<Pair<Int, Int>>()
+val harmonicAntinodeSet = mutableSetOf<Pair<Int, Int>>()
+var xMax = 0
+var yMax = 0
+while (scanner.hasNext()) {
+    val symbols = scanner.nextLine().trim().split("").filter { it.isNotEmpty() }
+    xMax = xMax.coerceAtLeast(symbols.lastIndex)
+    for ((i, symbol) in symbols.withIndex()) {
+        if (symbol == ".") continue
+        antennaMap.getOrPut(symbol) { mutableListOf() }.add(Pair(i, yMax))
+    }
+    yMax++
+}
+yMax--
+
+fun getAntinodes(pair: Pair<Int, Int>, pair1: Pair<Int, Int>, xMax: Int, yMax: Int): Collection<Pair<Int, Int>> {
+    val antinodes = mutableSetOf<Pair<Int, Int>>()
+    val diffOne = Pair(pair.first - pair1.first, pair.second - pair1.second)
+    antinodes.add(Pair(pair.first + diffOne.first, pair.second + diffOne.second))
+    antinodes.add(Pair(pair1.first - diffOne.first, pair1.second - diffOne.second))
+    antinodes.removeIf { it.first < 0 || it.second < 0 || it.first > xMax || it.second > yMax }
+    return antinodes
+}
+
+fun getHarmonicAntiNodes(
+    pair: Pair<Int, Int>,
+    pair1: Pair<Int, Int>,
+    xMax: Int,
+    yMax: Int
+): Collection<Pair<Int, Int>> {
+    val antinodes = mutableSetOf<Pair<Int, Int>>()
+    val diffOne = Pair(pair.first - pair1.first, pair.second - pair1.second)
+    var mult = 0
+    while ((pair.first + mult * diffOne.first) <= xMax && (pair.second + mult * diffOne.second) <= yMax && 0 <= (pair.first + mult * diffOne.first) && 0 <= (pair.second + mult * diffOne.second) ) {
+        antinodes.add(Pair(pair.first + mult * diffOne.first, pair.second + mult * diffOne.second))
+        mult++
+    }
+    mult = 0
+    while ((pair1.first - mult * diffOne.first) <= xMax && (pair1.second - mult * diffOne.second) <= yMax && 0 <= (pair1.first - mult * diffOne.first) && 0 <= (pair1.second - mult * diffOne.second)) {
+        antinodes.add(Pair(pair1.first - mult * diffOne.first, pair1.second - mult * diffOne.second))
+        mult++
+    }
+    antinodes.removeIf { it.first < 0 || it.second < 0 || it.first > xMax || it.second > yMax }
+    return antinodes
+}
+
+
+for (antennaType in antennaMap.keys) {
+    for (i in antennaMap[antennaType]!!.indices) {
+        for (y in (i + 1)..(antennaMap[antennaType]!!.lastIndex)) {
+            val antinodes = getAntinodes(antennaMap[antennaType]!![i], antennaMap[antennaType]!![y], xMax, yMax)
+            val harmonicAntinodes = getHarmonicAntiNodes(antennaMap[antennaType]!![i], antennaMap[antennaType]!![y], xMax, yMax)
+            antinodeSet.addAll(antinodes)
+            harmonicAntinodeSet.addAll(harmonicAntinodes)
+        }
+    }
+}
+
+fun printMap(antinodeSet: Set<Pair<Int, Int>>) {
+    for (y in 0..yMax) {
+        for (x in 0..xMax) {
+            if (Pair(x, y) in antennaMap.values.flatten()) {
+                for (antennatype in antennaMap.keys) {
+                    if (Pair(x, y) in antennaMap[antennatype]!!) {
+                        print(antennatype)
+                        break
+                    }
+                }
+            } else if(Pair(x, y) in antinodeSet) print("#") else print(".")
+        }
+        println()
+    }
+}
+
+println("Antinodes: ${antinodeSet.size}")
+println("Harmonic Antinodes: ${harmonicAntinodeSet.size}")