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No need to have two different recursion functions for Day 11. Tidied up.

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Chris Hodges 2025-12-11 07:55:54 +01:00
parent 0192b33570
commit 2190f9e1ac
1 changed files with 18 additions and 31 deletions
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49
src/aoc2025/Day11.kt
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@ -38,16 +38,6 @@ ggg: out
hhh: out
"""
data class Node(val name: String, val children: Set<Node>)
fun rec(children: HashMap<String, MutableSet<String>>, p: String, visited: MutableSet<String>): Int {
if (p == "out") return 1
visited.add(p)
val res = children[p]!!.sumOf { rec(children, it, visited) }
visited.remove(p)
return res
}
fun parseInput(input: List<String>): HashMap<String, MutableSet<String>> {
val children = HashMap<String, MutableSet<String>>()
for (i in input) {
@ -58,13 +48,7 @@ hhh: out
return children
}
fun part1(input: List<String>): Int {
val children = parseInput(input)
return rec(children, "you", HashSet())
}
fun rec2(
fun rec(
children: HashMap<String, MutableSet<String>>,
p: String,
stop: String,
@ -72,24 +56,27 @@ hhh: out
memo: HashMap<String, Long> = HashMap()
): Long {
if (p == stop) return 1L
val memoVal = memo[p]
if (memoVal != null) return memoVal
visited.add(p)
val res = children[p]?.sumOf { rec2(children, it, stop, visited, memo) } ?: 0L
visited.remove(p)
memo[p] = res
return res
return memo.getOrPut(p) {
visited.add(p)
val res = children[p]?.sumOf { rec(children, it, stop, visited, memo) } ?: 0L
visited.remove(p)
res
}
}
fun part1(input: List<String>): Long {
return rec(parseInput(input), "you", "out")
}
fun part2(input: List<String>): Long {
val children = parseInput(input)
val srvToDac = rec2(children, "svr", "dac")
val dacToFft = rec2(children, "dac", "fft")
val fftToOut = rec2(children, "fft", "out")
val srvToFft = rec2(children, "svr", "fft")
val fftToDac = rec2(children, "fft", "dac")
val dacToOut = rec2(children, "dac", "out")
val srvToDac = rec(children, "svr", "dac")
val dacToFft = rec(children, "dac", "fft")
val fftToOut = rec(children, "fft", "out")
val srvToFft = rec(children, "svr", "fft")
val fftToDac = rec(children, "fft", "dac")
val dacToOut = rec(children, "dac", "out")
return srvToDac * dacToFft * fftToOut + srvToFft * fftToDac * dacToOut
}
@ -102,7 +89,7 @@ hhh: out
println("Part 1 Test: $testInputPart1Result")
val testInputPart2Result = part2(testInput2)
println("Part 2 Test: $testInputPart2Result")
check(testInputPart1Result == 5)
check(testInputPart1Result == 5L)
check(testInputPart2Result == 2L)
val input = readInput("aoc2025/Day11")