Day05 2021

2021-12-05 15:47:12 +01:00
parent 81a488aaee
commit c3e8e6320e
3 changed files with 572 additions and 0 deletions
@@ -0,0 +1,50 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.BaseDay
+import be.vandewalleh.aoc.utils.input.Day
+
+@Day
+class Day05 : BaseDay() {
+
+    data class Point(val x: Int, val y: Int)
+
+    private val re = "(\\d+),(\\d+) -> (\\d+),(\\d+)".toRegex()
+
+    private fun path(start: Point, end: Point): Sequence<Point> {
+        val dx = end.x.compareTo(start.x)
+        val dy = end.y.compareTo(start.y)
+        return generateSequence(start) {
+            if (it == end) null
+            else Point(it.x + dx, it.y + dy)
+        }
+    }
+
+    override fun part1(): Int {
+        val visited = HashMap<Point, Int>()
+        input.lines.value
+            .map {
+                re.find(it)!!.destructured.let { (x1, y1, x2, y2) ->
+                    Point(x1.toInt(), y1.toInt()) to Point(x2.toInt(), y2.toInt())
+                }
+            }
+            .filter { (start, end) -> start.x == end.x || start.y == end.y }
+            .flatMap { (start, end) -> path(start, end) }
+            .forEach { visited.compute(it) { _, value -> (value ?: 0) + 1 } }
+
+        return visited.values.count { it >= 2 }
+    }
+
+    override fun part2(): Int {
+        val visited = HashMap<Point, Int>()
+        input.lines.value
+            .map {
+                re.find(it)!!.destructured.let { (x1, y1, x2, y2) ->
+                    Point(x1.toInt(), y1.toInt()) to Point(x2.toInt(), y2.toInt())
+                }
+            }
+            .flatMap { (start, end) -> path(start, end) }
+            .forEach { visited.compute(it) { _, value -> (value ?: 0) + 1 } }
+
+        return visited.values.count { it >= 2 }
+    }
+}