Add corners solution to 2024 day 12 part 2

sim642 · Dec 12, 2024 · 468a33b · 468a33b
1 parent 1fab106
commit 468a33b
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Showing 2 changed files with 56 additions and 20 deletions.
diff --git a/src/main/scala/eu/sim642/adventofcode2024/Day12.scala b/src/main/scala/eu/sim642/adventofcode2024/Day12.scala
@@ -47,6 +47,18 @@ object Day12 {
 
       BFS.components(graphComponents).size
     }
+
+    def corners: Int = {
+      (for {
+        pos <- poss.iterator
+        offset <- Pos.axisOffsets
+        rightPos = pos + offset // right of diagPos
+        leftPos = pos + offset.left // left of diagPos
+        diagPos = leftPos + offset
+        if !poss(rightPos) && !poss(leftPos) || poss(rightPos) && poss(leftPos) && !poss(diagPos) // if is external or internal corner
+        //if !poss(rightPos) && (!poss(leftPos) || poss(diagPos)) // from glguy: actually counts beginning of side, not corner itself
+      } yield pos).size
+    }
   }
 
   def regions(grid: Grid[Char]): collection.Set[Region] = {
@@ -78,16 +90,22 @@ object Day12 {
     override def regionFencingPrice(region: Region): Int = region.area * region.perimeter
   }
 
-  object Part2 extends Part {
+  trait Part2Solution extends Part
+
+  object SidesPart2Solution extends Part2Solution {
     override def regionFencingPrice(region: Region): Int = region.area * region.sides
   }
 
+  object CornersPart2Solution extends Part2Solution {
+    override def regionFencingPrice(region: Region): Int = region.area * region.corners
+  }
+
   def parseGrid(input: String): Grid[Char] = input.linesIterator.map(_.toVector).toVector
 
   lazy val input: String = scala.io.Source.fromInputStream(getClass.getResourceAsStream("day12.txt")).mkString.trim
 
   def main(args: Array[String]): Unit = {
     println(Part1.totalFencingPrice(parseGrid(input)))
-    println(Part2.totalFencingPrice(parseGrid(input)))
+    println(CornersPart2Solution.totalFencingPrice(parseGrid(input)))
   }
 }
diff --git a/src/test/scala/eu/sim642/adventofcode2024/Day12Test.scala b/src/test/scala/eu/sim642/adventofcode2024/Day12Test.scala
@@ -1,9 +1,17 @@
 package eu.sim642.adventofcode2024
 
-import Day12._
+import Day12.*
+import Day12Test.*
+import org.scalatest.Suites
 import org.scalatest.funsuite.AnyFunSuite
 
-class Day12Test extends AnyFunSuite {
+class Day12Test extends Suites(
+  new Part1Test,
+  new SidesPart2SolutionTest,
+  new CornersPart2SolutionTest,
+)
+
+object Day12Test {
 
   val exampleInput =
     """AAAA
@@ -45,25 +53,35 @@ class Day12Test extends AnyFunSuite {
       |ABBAAA
       |AAAAAA""".stripMargin
 
-  test("Part 1 examples") {
-    assert(Part1.totalFencingPrice(parseGrid(exampleInput)) == 140)
-    assert(Part1.totalFencingPrice(parseGrid(exampleInput2)) == 772)
-    assert(Part1.totalFencingPrice(parseGrid(exampleInput3)) == 1930)
-  }
+  class Part1Test extends AnyFunSuite {
 
-  test("Part 1 input answer") {
-    assert(Part1.totalFencingPrice(parseGrid(input)) == 1433460)
-  }
+    test("Part 1 examples") {
+      assert(Part1.totalFencingPrice(parseGrid(exampleInput)) == 140)
+      assert(Part1.totalFencingPrice(parseGrid(exampleInput2)) == 772)
+      assert(Part1.totalFencingPrice(parseGrid(exampleInput3)) == 1930)
+    }
 
-  test("Part 2 examples") {
-    assert(Part2.totalFencingPrice(parseGrid(exampleInput)) == 80)
-    assert(Part2.totalFencingPrice(parseGrid(exampleInput2)) == 436)
-    assert(Part2.totalFencingPrice(parseGrid(exampleInput4)) == 236)
-    assert(Part2.totalFencingPrice(parseGrid(exampleInput5)) == 368)
-    assert(Part2.totalFencingPrice(parseGrid(exampleInput3)) == 1206)
+    test("Part 1 input answer") {
+      assert(Part1.totalFencingPrice(parseGrid(input)) == 1433460)
+    }
   }
 
-  test("Part 2 input answer") {
-    assert(Part2.totalFencingPrice(parseGrid(input)) == 855082)
+  abstract class Part2SolutionTest(part2Solution: Part2Solution) extends AnyFunSuite {
+
+    test("Part 2 examples") {
+      assert(part2Solution.totalFencingPrice(parseGrid(exampleInput)) == 80)
+      assert(part2Solution.totalFencingPrice(parseGrid(exampleInput2)) == 436)
+      assert(part2Solution.totalFencingPrice(parseGrid(exampleInput4)) == 236)
+      assert(part2Solution.totalFencingPrice(parseGrid(exampleInput5)) == 368)
+      assert(part2Solution.totalFencingPrice(parseGrid(exampleInput3)) == 1206)
+    }
+
+    test("Part 2 input answer") {
+      assert(part2Solution.totalFencingPrice(parseGrid(input)) == 855082)
+    }
   }
+
+  class SidesPart2SolutionTest extends Part2SolutionTest(SidesPart2Solution)
+
+  class CornersPart2SolutionTest extends Part2SolutionTest(CornersPart2Solution)
 }