77 lines
1.6 KiB
Go
77 lines
1.6 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/position"
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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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numOfRows := len(input)
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numOfCols := len(input[0])
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startRow := -1
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startCol := -1
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for row := range numOfRows - 1 {
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for col := range numOfCols - 1 {
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v := string(input[row][col])
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if v == StartCharacter {
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startRow = row
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startCol = col
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break
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}
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}
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}
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if startRow < 0 || startCol < 0 {
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panic("unable to find start location")
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}
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beamStart := position.From(startRow+1, startCol)
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beamsQueue := []position.Position{
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beamStart,
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}
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visited := map[position.Position]bool{}
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total := 0
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for len(beamsQueue) > 0 {
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currentBeam := beamsQueue[0]
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beamsQueue = beamsQueue[1:]
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if visited[currentBeam] {
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continue
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}
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if currentBeam.Row() < 0 || currentBeam.Row() >= numOfRows {
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continue
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}
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if currentBeam.Column() < 0 || currentBeam.Column() >= numOfCols {
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continue
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}
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visited[currentBeam] = true
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value := string(input[currentBeam.Row()][currentBeam.Column()])
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if value == SplitterCharacter {
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total++
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rightBeam := position.From(currentBeam.Row(), currentBeam.Column()+1)
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leftBeam := position.From(currentBeam.Row(), currentBeam.Column()-1)
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beamsQueue = append(beamsQueue, rightBeam, leftBeam)
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continue
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}
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nextBeam := position.From(currentBeam.Row()+1, currentBeam.Column())
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beamsQueue = append(beamsQueue, nextBeam)
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}
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return total
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}
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