Day03

2020-12-03 07:09:36 +01:00
parent 5c401d8ae0
commit 6ab2fbce00
2 changed files with 374 additions and 0 deletions
@@ -0,0 +1,51 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.Day
+import be.vandewalleh.aoc.utils.input.Input
+import be.vandewalleh.aoc.utils.input.Lines
+import be.vandewalleh.aoc.utils.input.createDay
+
+data class Slope(val x: Int, val y: Int)
+
+@Day(3)
+class Day03(@Lines val input: Input<List<String>>) {
+
+    fun part1(slope: Slope = Slope(x = 3, y = 1)): Int {
+        val grid = input.value
+        var trees = 0
+        var x = 0
+        var y = 0
+
+        val width = grid.first().length
+
+        while (true) {
+            x += slope.x
+            y += slope.y
+
+            if (x >= width) x -= width
+            if (y >= grid.size) break
+            if (grid[y][x] == '#') trees++
+        }
+
+        return trees
+    }
+
+    fun part2(): Long = listOf(
+        Slope(x = 1, y = 1),
+        Slope(x = 3, y = 1),
+        Slope(x = 5, y = 1),
+        Slope(x = 7, y = 1),
+        Slope(x = 1, y = 2),
+    )
+        .map { it to part1(it) }
+        .onEach { println("$it") }
+        .map { it.second.toLong() }
+        .reduce { acc, trees -> acc * trees }
+}
+
+fun main() {
+    with(createDay<Day03>()) {
+        println(part1().also { check(it == 294) })
+        println(part2().also { check(it == 5774564250) })
+    }
+}