Solved day13 part 2

Author: Gentleman1983

build.gradle

@@ -4,7 +4,7 @@ plugins {
 
 // project meta data
 group 'de.havox_design.aoc2023'
-version '0.12.3'
+version '0.12.4'
 
 // Switch to gradle "all" distribution.
 wrapper {

day13/src/main/kotlin/de/havox_design/aoc2023/day13/Day13.kt

@@ -7,7 +7,9 @@ class Day13(private var filename: String) {
             .toLong()
 
     fun solvePart2(): Long =
-        400L
+        makePatterns(getResourceAsText(filename))
+            .sumOf { it.smudgeMirrorValue() }
+            .toLong()
 
     private fun makePatterns(input: List<String>): List<Pattern> {
         return input

day13/src/main/kotlin/de/havox_design/aoc2023/day13/Pattern.kt

@@ -1,6 +1,8 @@
 package de.havox_design.aoc2023.day13
 
 data class Pattern(val rows: List<String>) {
+    private val ICON_ASH = '.'
+    private val ICON_ROCK = '#'
     private val numColumns = rows[0].length
 
     override fun toString(): String {
@@ -22,10 +24,28 @@ data class Pattern(val rows: List<String>) {
             .filter(::isMirrorColumn)
             .map { it + 1 }
 
-        return (rowScores + columnScores)
+        return (rowScores + columnScores + 0)
             .first { it != pleaseDoNotBe }
     }
 
+    fun smudgeMirrorValue(): Int {
+        val originalValue = mirrorValue()
+
+        for (rowIndex in rows.indices) {
+            for (columnIndex in rows[0].indices) {
+                val pattern = Pattern(rows.flipMirror(rowIndex, columnIndex))
+                val newValue = pattern.mirrorValue(originalValue)
+
+                when {
+                    newValue != 0 && newValue != originalValue -> {
+                        return newValue
+                    }
+                }
+            }
+        }
+        return originalValue
+    }
+
     @SuppressWarnings("kotlin:S6510")
     private fun isMirrorRow(index: Int): Boolean {
         var top = index
@@ -75,4 +95,16 @@ data class Pattern(val rows: List<String>) {
             }
         }
     }
+
+    private fun List<String>.flipMirror(rowIndex: Int, columnIndex: Int): List<String> {
+        val mutableList = this.toMutableList()
+        val rowToReplace = mutableList[rowIndex].toMutableList()
+        rowToReplace[columnIndex] = when {
+            rowToReplace[columnIndex] == ICON_ASH -> ICON_ROCK
+            else -> ICON_ASH
+        }
+        mutableList[rowIndex] = rowToReplace.joinToString("")
+
+        return mutableList.toList()
+    }
 }

day13/src/test/kotlin/de/havox_design/aoc2023/day13/Day13Test.kt

@@ -27,13 +27,13 @@ class Day13Test {
         @JvmStatic
         private fun getDataForTestSolvePart1(): Stream<Arguments> =
             Stream.of(
-                Arguments.of("part1sample.txt", 405L)
+                Arguments.of("sample.txt", 405L)
             )
 
         @JvmStatic
         private fun getDataForTestSolvePart2(): Stream<Arguments> =
             Stream.of(
-                Arguments.of("part2sample1.txt", 400L)
+                Arguments.of("sample.txt", 400L)
             )
     }
 }