2025, Day 7

Author: edgars-supe

.idea/runConfigurations/2025__Day_7.xml

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+package lv.esupe.aoc.year2025
+
+import lv.esupe.aoc.Puzzle
+import lv.esupe.aoc.model.Grid
+import lv.esupe.aoc.model.Point
+import lv.esupe.aoc.solve
+import lv.esupe.aoc.utils.memoize
+
+fun main() = solve { Day7() }
+
+class Day7 : Puzzle<Int, Long>(2025, 7) {
+    override val input = Grid.from(rawInput)
+    private val start = input.firstNotNullOf { it.takeIf { it.value == 'S' } }
+    private val numTimelines = memoize(::_numTimelines)
+
+    override fun solvePartOne(): Int {
+        val queue = mutableSetOf(start.key)
+        var splits = 0
+        while (queue.isNotEmpty()) {
+            val p = queue.first()
+            queue.remove(p)
+            val newP = p.up()
+            if (input[newP] == '^') {
+                queue.add(newP.left())
+                queue.add(newP.right())
+                splits++
+            } else if (input.isInBounds(newP)) {
+                queue.add(newP)
+            }
+        }
+        return splits
+    }
+
+    override fun solvePartTwo(): Long {
+        return numTimelines(start.key)
+    }
+
+    private fun _numTimelines(from: Point): Long {
+        val newP = from.up()
+        return when {
+            input[newP] == '^' -> numTimelines(newP.left()) + numTimelines(newP.right())
+            input.isInBounds(newP) -> numTimelines(newP)
+            else -> 1L
+        }
+    }
+}

src/main/kotlin/lv/esupe/aoc/year2025/Day7.kt

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+package lv.esupe.aoc.year2025
+
+import lv.esupe.aoc.DayTest
+import org.junit.jupiter.api.Test
+
+class Day7Test : DayTest<Int, Long>() {
+    override val puzzle = { Day7() }
+
+    @Test
+    fun day7_1() {
+        runTest("_1", 21, 40)
+    }
+}

src/test/kotlin/lv/esupe/aoc/year2025/Day7Test.kt

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+.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............