1 files changed, 57 insertions, 0 deletions
diff --git a/src/Day17.kt b/src/Day17.kt
index 32f47fe..5eaf498 100644
--- a/src/Day17.kt
+++ b/src/Day17.kt
@@ -1,3 +1,60 @@
+import kotlin.math.max
+import kotlin.math.sign
+
+data class Target(val left: Int, val right: Int, val bottom: Int, val top: Int)
+
+class Probe(private var vel: Pos2D, private val target: Target) {
+    companion object {
+        fun search(target: Target): Pair<Int, Int> {
+            var highest = 0
+            var count = 0
+
+            for (vx in 0..1000) {
+                for (vy in -1000..1000) {
+                    val probe = Probe(Pos2D(vx, vy), target)
+                    var currentHighest = 0
+
+                    while (probe.canHitTarget) {
+                        probe.step()
+                        currentHighest = max(currentHighest, probe.pos.y)
+
+                        if (probe.isInTarget) {
+                            count++
+                            highest = max(highest, currentHighest)
+                            break
+                        }
+                    }
+                }
+            }
+
+            return highest to count
+        }
+    }
+
+    private var pos = Pos2D(0, 0)
+
+    fun step() {
+        pos += vel
+        vel = vel.copy(x = vel.x - vel.x.sign, y = vel.y - 1)
+    }
+
+    val canHitTarget
+        get() = pos.y > target.bottom
+
+    val isInTarget
+        get() = pos.x in target.left..target.right && pos.y in target.bottom..target.top
+}
+
 fun main() {
+    fun bothParts(input: Target): Pair<Int, Int> = Probe.search(input)
+
+    val testInput = Target(20, 30, -10, -5)
+    val testOutput = bothParts(testInput)
+    check(testOutput.first == 45)
+    check(testOutput.second == 112)
 
+    val input = Target(192, 251, -89, -59)
+    val output = bothParts(input)
+    println(output.first)
+    println(output.second)
 }