Solve 2018 day 8 part 2

sim642 · sim642 · commit 7bd0760af5b9 · 2018-12-08T11:30:45.000+02:00
diff --git a/src/main/scala/eu/sim642/adventofcode2018/Day8.scala b/src/main/scala/eu/sim642/adventofcode2018/Day8.scala
@@ -6,6 +6,18 @@ object Day8 {
 
   def metadataSum(tree: Tree): Int = tree.childen.map(metadataSum).sum + tree.metadata.sum
 
+  def value(tree: Tree): Int = {
+    if (tree.childen.isEmpty)
+      tree.metadata.sum
+    else {
+      tree.metadata
+        .filter(i => 1 <= i && i <= tree.childen.length)
+        .map(i => tree.childen(i - 1))
+        .map(value)
+        .sum
+    }
+  }
+
   def parseTree(seq: List[Int]): Tree = {
     def helper(seq: List[Int]): (Tree, List[Int]) = seq match {
       case childrenCount :: metadataCount :: tl =>
@@ -29,5 +41,6 @@ object Day8 {
 
   def main(args: Array[String]): Unit = {
     println(metadataSum(parseTree(input)))
+    println(value(parseTree(input)))
   }
 }
diff --git a/src/test/scala/eu/sim642/adventofcode2018/Day8Test.scala b/src/test/scala/eu/sim642/adventofcode2018/Day8Test.scala
@@ -14,4 +14,12 @@ class Day8Test extends FunSuite {
   test("Part 1 input answer") {
     assert(metadataSum(parseTree(input)) == 46578)
   }
+
+  test("Part 2 examples") {
+    assert(value(parseTree(exampleInput)) == 66)
+  }
+
+  test("Part 2 input answer") {
+    assert(value(parseTree(input)) == 31251)
+  }
 }

Original file line number	Diff line number	Diff line change
`@@ -14,4 +14,12 @@ class Day8Test extends FunSuite {`
`14`	`14`	`test("Part 1 input answer") {`
`15`	`15`	`assert(metadataSum(parseTree(input)) == 46578)`
`16`	`16`	`}`
	`17`	`+`
	`18`	`+ test("Part 2 examples") {`
	`19`	`+ assert(value(parseTree(exampleInput)) == 66)`
	`20`	`+ }`
	`21`	`+`
	`22`	`+ test("Part 2 input answer") {`
	`23`	`+ assert(value(parseTree(input)) == 31251)`
	`24`	`+ }`
`17`	`25`	`}`