Solve part 2 day 10

Author: michaeltroger

src/Day10.kt

@@ -3,7 +3,7 @@ private const val DAY = 10
 fun main() {
     fun part1(input: List<String>): Int {
         var syntaxErrorScore = 0
-        input.mapIndexed { lineNumber, line ->
+        input.map { line ->
             val expectedCloseSigns = mutableListOf<Char>()
             line.forEach { actualChar ->
                 when(actualChar) {
@@ -12,8 +12,7 @@ fun main() {
                     '{' -> expectedCloseSigns.add('}')
                     '<' -> expectedCloseSigns.add('>')
                     ']', ')', '}', '>' -> {
-                        val expected = expectedCloseSigns.removeLast()
-                        if (expected != actualChar) {
+                        if (expectedCloseSigns.removeLast() != actualChar) {
                             syntaxErrorScore += getSyntaxErrorPoints(actualChar)
                             return@forEach
                         }
@@ -25,24 +24,75 @@ fun main() {
         return syntaxErrorScore
     }
 
-    fun part2(input: List<String>): Int {
-        return -1
+    fun part2(input: List<String>): Long {
+        val totalScoresLines = mutableListOf<Long>()
+        val incompleteLines = input.removeCorruptedLines()
+        incompleteLines.map { line ->
+            val expectedCloseSigns = mutableListOf<Char>()
+            line.forEach { actualChar ->
+                when(actualChar) {
+                    '[' -> expectedCloseSigns.add(']')
+                    '(' -> expectedCloseSigns.add(')')
+                    '{' -> expectedCloseSigns.add('}')
+                    '<' -> expectedCloseSigns.add('>')
+                    ']', ')', '}', '>' -> expectedCloseSigns.removeLast()
+                }
+            }
+            var totalScore = 0L
+            expectedCloseSigns.reversed().forEach { char ->
+                totalScore *= 5
+                totalScore += getAutocompletePoints(char)
+            }
+            totalScoresLines.add(totalScore)
+        }
+
+        return totalScoresLines.sorted()[totalScoresLines.size / 2]
     }
 
     // test if implementation meets criteria from the description, like:
     val testInput = readInput(day = DAY, useTestInput = true)
     check(part1(testInput) == 26397)
-    //check(part2(testInput) == 1134)
+    check(part2(testInput) == 288957L)
 
     val input = readInput(day = DAY)
     println(part1(input))
     println(part2(input))
 }
 
+private fun List<String>.removeCorruptedLines(): List<String> {
+    return filter { line ->
+        val expectedCloseSigns = mutableListOf<Char>()
+        var isLegal = true
+        line.forEach { actualChar ->
+            when(actualChar) {
+                '[' -> expectedCloseSigns.add(']')
+                '(' -> expectedCloseSigns.add(')')
+                '{' -> expectedCloseSigns.add('}')
+                '<' -> expectedCloseSigns.add('>')
+                ']', ')', '}', '>' -> {
+                    if (expectedCloseSigns.removeLast() != actualChar) {
+                        isLegal = false
+                        return@forEach
+                    }
+                }
+            }
+        }
+        isLegal
+    }
+}
+
 private fun getSyntaxErrorPoints(char: Char) = when (char) {
     ')' -> 3
     ']' -> 57
     '}' -> 1197
     '>' -> 25137
     else -> throw Error("unexpected char")
+}
+
+private fun getAutocompletePoints(char: Char) = when (char) {
+    ')' -> 1
+    ']' -> 2
+    '}' -> 3
+    '>' -> 4
+    else -> throw Error("unexpected char")
 }