Solution Day 14, part one

Author: rhaendel

src/main/kotlin/Day14.kt

@@ -0,0 +1,78 @@
+fun main() {
+    val day = "Day14"
+
+    val robotPattern = """p=(\d+),(\d+) v=(-?\d+),(-?\d+)""".toRegex()
+
+    println("$day part 1")
+
+    fun List<String>.parseRobots() = map {
+        val (px, py, vx, vy) = robotPattern.find(it)!!.destructured
+        Robot(px.toInt(), py.toInt(), vx.toInt(), vy.toInt())
+    }
+
+    fun List<Robot>.move(width: Int, height: Int, seconds: Int) = map {
+        it.copy(
+            px = (it.px + seconds * it.vx).mod(width),
+            py = (it.py + seconds * it.vy).mod(height),
+        )
+    }
+
+    fun List<Robot>.countQuadrants(width: Int, height: Int) = fold(QuadrantCounts(0, 0, 0, 0)) { counts, it ->
+        if (it.px in 0..<width / 2 && it.py in 0..<height / 2) {
+            counts.q1++
+        }
+        if (it.px in width / 2 + 1..width && it.py in 0..<height / 2) {
+            counts.q2++
+        }
+        if (it.px in 0..<width / 2 && it.py in height / 2 + 1..height) {
+            counts.q3++
+        }
+        if (it.px in width / 2 + 1..width && it.py in height / 2 + 1..height) {
+            counts.q4++
+        }
+        counts
+    }
+
+    fun part1Small(input: List<String>): Int {
+        val width = 11
+        val height = 7
+        val (q1, q2, q3, q4) = input.parseRobots()
+            .move(width, height, 100)
+            .countQuadrants(width, height)
+        return q1 * q2 * q3 * q4
+    }
+
+    fun part1(input: List<String>): Int {
+        val width = 101
+        val height = 103
+        val (q1, q2, q3, q4) = input.parseRobots()
+            .move(width, height, 100)
+            .countQuadrants(width, height)
+        return q1 * q2 * q3 * q4
+    }
+
+    printAndCheck(
+        """
+            p=0,4 v=3,-3
+            p=6,3 v=-1,-3
+            p=10,3 v=-1,2
+            p=2,0 v=2,-1
+            p=0,0 v=1,3
+            p=3,0 v=-2,-2
+            p=7,6 v=-1,-3
+            p=3,0 v=-1,-2
+            p=9,3 v=2,3
+            p=7,3 v=-1,2
+            p=2,4 v=2,-3
+            p=9,5 v=-3,-3
+        """.trimIndent().lines(),
+        ::part1Small, 12
+    )
+
+    val input = readInput(day)
+    printAndCheck(input, ::part1, 218433348)
+}
+
+data class Robot(val px: Int, val py: Int, val vx: Int, val vy: Int)
+
+data class QuadrantCounts(var q1: Int, var q2: Int, var q3: Int, var q4: Int)