Day7 solved.

Author: Mateusz Becker

src/main/kotlin/com/advent/d7/Day7.kt

@@ -0,0 +1,151 @@
+package com.advent.d7
+
+import com.advent.d7.Day7.Operation
+import com.advent.d7.Day7.toOperation
+import com.advent.readLinesFromFile
+import java.util.*
+
+/**
+ * @author Mateusz Becker
+ */
+fun main() {
+
+//    val input = Day7.exampleData()
+    val input = readLinesFromFile("input_d7.txt")
+
+    data class File(val fileName: String, val size: Long)
+    data class Dir(
+        val name: String,
+        val parent: Dir?,
+        val directories: MutableList<Dir>,
+        val files: MutableList<File>,
+        var size: Long
+    ) {
+        override fun toString(): String {
+            return "DIR: ${name},  ${size}, ${files}"
+//            return "DIR: ${name},  ${size}, ${files},\n $directories"
+        }
+    }
+
+    fun scanLinesForDirsAndFiles(): Dir {
+        var operation: Operation = Operation.CD
+
+        var currentDir = Dir("/", null, mutableListOf(), mutableListOf(), 0)
+        val rootDir = currentDir
+
+        for (line in input) {
+            val content = line.split(" ")
+            if (content[0] == "${'$'}") {
+                operation = content[1].toOperation()
+            }
+            when (operation) {
+                Operation.CD -> {
+                    val name = content[2]
+                    if (name == "..") {
+                        currentDir = currentDir.parent!!
+                    } else {
+                        if (name != "/") {
+                            currentDir = Dir(name, currentDir, mutableListOf(), mutableListOf(), 0)
+                            currentDir.parent!!.directories += currentDir
+                        }
+                    }
+                }
+                Operation.LS -> {
+                    content[0].toLongOrNull()?.let { size ->
+                        currentDir.files += File(content[1], size)
+                    }
+                }
+            }
+        }
+        return rootDir
+    }
+
+    val dirs = PriorityQueue<Dir>(Comparator.comparing { dir -> dir.size })
+
+    fun computeSizeInDirsRecursive(currentDir: Dir) {
+        for (dir in currentDir.directories) {
+            computeSizeInDirsRecursive(dir)
+        }
+        val filesSize = currentDir.files.fold(0L) { acc, file -> file.size + acc }
+        val dirsSize = currentDir.directories.fold(0L) { acc, dir -> dir.size + acc }
+        currentDir.size = dirsSize + filesSize
+
+        dirs += currentDir
+    }
+
+    val rootDir = scanLinesForDirsAndFiles()
+    computeSizeInDirsRecursive(rootDir)
+    val dirs2 = PriorityQueue(dirs)
+
+    fun part1Answer(dirs: Queue<Dir>): Long {
+        var size: Long = 0
+        var acc: Long = 0
+        while (dirs.isNotEmpty()) {
+            size = dirs.poll().size
+            if (size > 100_000) {
+                break
+            }
+            acc += size
+        }
+        return acc
+    }
+
+    val answer = part1Answer(dirs)
+    println("Day7 part 1 answer: $answer")
+
+    val diskSpace: Long = 70000000
+    val minDiscSpace: Long = 30000000
+    val toDelete = minDiscSpace - (diskSpace - rootDir.size)
+
+    fun part2Answer(dirs: Queue<Dir>): Long {
+        var size: Long
+        do {
+            size = dirs.poll().size
+        } while (size < toDelete)
+
+        return size
+    }
+
+    val answer2 = part2Answer(dirs2)
+    println("Day7 part 2 answer: $answer2")
+
+}
+
+
+object Day7 {
+    fun exampleData() = """
+${'$'} cd /
+${'$'} ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+${'$'} cd a
+${'$'} ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+${'$'} cd e
+${'$'} ls
+584 i
+${'$'} cd ..
+${'$'} cd ..
+${'$'} cd d
+${'$'} ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k
+""".trimIndent()
+        .split("\n")
+
+    fun String.toOperation(): Operation {
+        return Operation.values().find { it.name.lowercase() == this }!!
+    }
+
+    enum class Operation {
+        LS, CD
+    }
+
+}