71 lines
1.4 KiB
Go
71 lines
1.4 KiB
Go
package main
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import (
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"github.com/StevanFreeborn/advent-of-code-2025/internal/file"
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"github.com/StevanFreeborn/advent-of-code-2025/internal/grid"
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"github.com/StevanFreeborn/advent-of-code-2025/internal/move"
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"github.com/StevanFreeborn/advent-of-code-2025/internal/position"
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"github.com/StevanFreeborn/advent-of-code-2025/internal/queue"
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)
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const StartCharacter = "S"
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const SplitterCharacter = "^"
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func SolvePartOne(filePath string) int {
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input := file.ReadAllLines(filePath)
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grid := grid.From(input)
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var startPosition position.Position
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for p, v := range grid.Positions() {
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if v == StartCharacter {
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startPosition = p
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break
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}
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}
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if startPosition == nil {
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panic("unable to find start location")
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}
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beamStart := startPosition.Move(move.Down)
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beamsQueue := queue.New[position.Position]()
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beamsQueue.Enqueue(beamStart)
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visited := map[position.Position]bool{}
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total := 0
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for beamsQueue.IsEmpty() == false {
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currentBeam, _ := beamsQueue.Dequeue()
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if visited[currentBeam] {
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continue
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}
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if grid.InBounds(currentBeam) == false {
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continue
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}
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visited[currentBeam] = true
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value := grid.GetValueAt(currentBeam)
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if value == SplitterCharacter {
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total++
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rightBeam := currentBeam.Move(move.Right)
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leftBeam := currentBeam.Move(move.Left)
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beamsQueue.Enqueue(rightBeam)
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beamsQueue.Enqueue(leftBeam)
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continue
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}
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nextBeam := currentBeam.Move(move.Down)
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beamsQueue.Enqueue(nextBeam)
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}
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return total
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}
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