updated progress in README

README.md

@@ -5,11 +5,11 @@ This repo contains my attempt at this year's Advent of Code (2023)
 I will try and do some problems (probably not all of them) in Scala
 
 ## Progress:
-#### Stars: 9 / 50
+#### Stars: 10 / 50
 |        Mon        |        Tue        | Wed | Thu |        Fri        |        Sat        |        Sun        |
-|:-----------------:|:-----------:|:---:|:---:|:-----------------:|:-----------------:|:-----------------:|
+|:-----------------:|:-----------------:|:---:|:---:|:-----------------:|:-----------------:|:-----------------:|
 |                   |                   |     |     | 1<br>:star::star: | 2<br>:star::star: | 3<br>:star::star: |
-| 4<br>:star::star: | 5<br>:star: |  6  |  7  |         8         |         9         |        10         |
+| 4<br>:star::star: | 5<br>:star::star: |  6  |  7  |         8         |         9         |        10         |
 |        11         |        12         | 13  | 14  |        15         |        16         |        17         |
 |        18         |        19         | 20  | 21  |        22         |        23         |        24         |
 |        25         |                   |     |     |                   |                   |                   |

src/day5/Puzzle2.scala

@@ -0,0 +1,208 @@
+package day5
+
+import scala.collection.mutable
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+  case class Range(startSrc: Long, startDst: Long, length: Long, dstTable: Int) {
+    def endSrc: Long = startSrc + length
+    def endDst: Long = startDst + length
+    def containsSrc(src: Long): Boolean = startSrc <= src && src < endSrc
+    def containsDst(dst: Long): Boolean = startDst <= dst && dst < endDst
+    def forward(src: Long): Long = startDst + src - startSrc
+    def backward(dst: Long): Long = startSrc + dst - startDst
+    override def toString: String = s"[$startSrc;$endSrc[ -> ($dstTable) [$startDst;$endDst["
+  }
+  class Table(val id: Int) {
+    var ranges: ArrayBuffer[Range] = new ArrayBuffer()
+
+    def addRange(range: Range): Unit = ranges.addOne(range)
+    def sortRanges(): Unit = {
+      var changed: Boolean = false
+      do {
+        changed = false
+        for (i: Int <- 0 until ranges.length-1) {
+          if (ranges(i).startSrc >= ranges(i + 1).startSrc + ranges(i + 1).length) {
+            changed = true
+            val range: Range = ranges(i)
+            ranges(i) = ranges(i + 1)
+            ranges(i + 1) = range
+          }
+        }
+      } while (changed)
+    }
+
+    def fillGaps(): Unit = {
+      var r1: Range = Range(0, 0, 0, id + 1)
+      var r2: Range = r1
+      var i: Int = 0
+      while (i < ranges.length) {
+        r2 = ranges(i)
+        val start: Long = r1.startSrc+r1.length
+        if (start != r2.startSrc) {
+          ranges.insert(i, Range(start, start, r2.startSrc - start, id+1))
+          i += 1
+        }
+        r1 = r2
+        i += 1
+      }
+    }
+
+    def forward(src: Long): (Long, Int) = {
+      for (range: Range <- ranges) {
+        if (range.containsSrc(src)) return (range.forward(src), range.dstTable)
+      }
+      return (src, id+1)
+    }
+    def backward(dst: Long): (Long, Int) = {
+      for (range: Range <- ranges) {
+        if (range.containsDst(dst)) return (range.backward(dst), id)
+      }
+      return (dst, id)
+    }
+
+    override def toString: String = s"Table $id:\n  " + ranges.mkString("\n  ")
+  }
+
+  var forwardingTables: Array[Table] = Array.empty
+  var seeds: Array[Long] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+
+    val almanac: String = source.getLines().mkString("\n")
+    val tables: Array[String] = almanac.split("\n\n")
+
+    forwardingTables = new Array(tables.length - 1)
+    seeds = tables(0).substring(7).split(" ").map(s => s.toLong)
+
+    for (i: Int <- 1 until tables.length) {
+      val lines: Array[String] = tables(i).split(":\n")(1).split("\n")
+      val table: Table = new Table(i-1)
+      for (line: String <- lines) {
+        val values: Array[Long] = line.split(" ").map(v => v.toLong)
+        table.addRange(Range(values(1), values(0), values(2), i))
+      }
+      forwardingTables(i-1) = table
+    }
+
+    source.close()
+  }
+
+  def sortTables(): Unit = {
+    for (table: Table <- forwardingTables) {
+      table.sortRanges()
+      table.fillGaps()
+    }
+  }
+
+  def simplifyTables(): Unit = {
+    for (i: Int <- forwardingTables.length - 1 until 0 by -1) {
+      //simplifyTable(i)
+      val newTable: Table = collapseTables(forwardingTables(i-1), forwardingTables(i))
+      forwardingTables(i-1) = newTable
+    }
+  }
+
+  def simplifyTable(tableI: Int): Unit = {
+    val table1: Table = forwardingTables(tableI)
+    val table2: Table = forwardingTables(tableI+1)
+
+    val newTable1: Table = new Table(table1.id)
+    val limits: ArrayBuffer[Long] = new ArrayBuffer()
+
+    for (r1: Range <- table1.ranges) {
+      val startFrom1 = r1.startSrc
+      val endFrom1 = startFrom1 + r1.length
+      val startTo1 = r1.startDst
+      val endTo1 = startTo1 + r1.length
+
+      limits.addOne(startTo1)
+      limits.addOne(endTo1)
+
+      for (r2: Range <- table2.ranges) {
+        val startFrom2 = r2.startSrc
+        val endFrom2 = startFrom2 + r2.length
+        val startTo2 = r2.startDst
+        val endTo2 = startTo2 + r2.length
+
+        limits.addOne(startFrom2)
+        limits.addOne(endFrom2)
+
+        // If overlap
+        if (!(endTo1 < startFrom2 || startTo1 > endFrom2)) {
+          
+        }
+      }
+    }
+
+    forwardingTables(tableI) = newTable1
+  }
+
+  def collapseTables(table1: Table, table2: Table): Table = {
+    val limitsSet: mutable.Set[Long] = new mutable.HashSet()
+    limitsSet.addOne(table1.ranges(0).startSrc)
+    for (range: Range <- table1.ranges) {
+      limitsSet.addOne(range.endSrc)
+    }
+    limitsSet.addOne(table1.backward(table2.ranges(0).startSrc)._1)
+    for (range: Range <- table2.ranges) {
+      limitsSet.addOne(table1.backward(range.endSrc)._1)
+    }
+
+    val newTable: Table = new Table(table1.id)
+    val limits: Array[Long] = limitsSet.toArray.sorted
+    for (i: Int <- 0 until limits.length - 1) {
+      val src1: Long = limits(i)
+      val dst1: (Long, Int) = table1.forward(src1)
+      if (dst1._2 != table2.id) throw new Exception("Something weird happened")
+      val dst2: (Long, Int) = table2.forward(dst1._1)
+      newTable.addRange(Range(src1, dst2._1, limits(i+1)-src1, dst2._2))
+    }
+    return newTable
+  }
+
+  def forward(value: Long, tableI: Int): Long = {
+    for (range: Range <- forwardingTables(tableI).ranges) {
+      if (value >= range.startSrc) {
+        if (value < range.startSrc + range.length) {
+          return value - range.startSrc + range.startDst
+        }
+      } else {
+        return value
+      }
+    }
+    return value
+  }
+  def solve(path: String): Long = {
+    println("Solving puzzle 2")
+    loadInput(path)
+    println("Loaded input")
+    sortTables()
+    for (table: Table <- forwardingTables) {
+      println(table)
+    }
+    println("Sorted forwarding tables")
+    simplifyTables()
+    println("Simplified forwarding tables")
+    val table: Table = forwardingTables(0)
+    println(table)
+
+    var smallest: Long = -1
+    for (i: Int <- seeds.indices by 2) {
+      println(s"Mapping range of seed [${seeds(i)},${seeds(i)+seeds(i+1)}]")
+      for (seed: Long <- seeds(i) until seeds(i)+seeds(i+1)) {
+        val location: Long = table.forward(seed)._1
+        if (smallest == -1 || location < smallest) {
+          smallest = location
+        }
+      }
+      println(s"New smallest location: $smallest")
+    }
+    return smallest
+  }
+  def main(args: Array[String]): Unit = {
+    val solution: Long = solve("res/day5/input1.txt")
+    println(solution)
+  }
+}

tests/day5/Puzzle2Test.scala

@@ -0,0 +1,9 @@
+package day5
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve") {
+    assert(Puzzle2.solve("tests_res/day5/input1.txt") == 46)
+  }
+}