From 4807b2a0332cf261bdf1f6899662403a39014ba1 Mon Sep 17 00:00:00 2001
From: Sven Weidauer <sven@5sw.de>
Date: Wed, 25 Dec 2024 12:25:32 +0100
Subject: [PATCH] Day 18 part 2

---
 2024/src/main/kotlin/day18.kt | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/2024/src/main/kotlin/day18.kt b/2024/src/main/kotlin/day18.kt
index 1959f2f..b1ac0f1 100644
--- a/2024/src/main/kotlin/day18.kt
+++ b/2024/src/main/kotlin/day18.kt
@@ -22,4 +22,28 @@ fun main() {
             .map { it to 1 }
     })
     println("Part 1: $distance")
+
+
+    val input = readInput("day18.txt")
+        .map {
+            val (a, b) = it.split(',', limit = 2)
+            Grid.Coordinate(a.toInt(), b.toInt())
+        }
+
+    val mem = CharGrid(size, size, '.')
+    for (location in input) {
+        mem[location] = '#'
+
+        val isStopped = dijkstra(start, goal = { it == goal }, neighbors = { pos ->
+            Direction.entries.asSequence()
+                .map { pos.step(it) }
+                .filter { it in mem && mem[it] == '.' }
+                .map { it to 1 }
+        }) == null
+
+        if (isStopped) {
+            println("Part 2: ${location.x},${location.y}")
+            break
+        }
+    }
 }
\ No newline at end of file