72 lines
1.2 KiB
Go
72 lines
1.2 KiB
Go
package three
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import (
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"bufio"
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"fmt"
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"os"
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)
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type forest struct {
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trees [][]bool
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rows, width int
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}
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func (f *forest) load(filename string) error {
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file, err := os.Open(filename)
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if err != nil {
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return err
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}
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defer file.Close()
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scanner := bufio.NewScanner(file)
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for scanner.Scan() {
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if f.rows == 0 {
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f.width = len(scanner.Text())
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}
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row := make([]bool, f.width)
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for position, possibleTree := range scanner.Text() {
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row[position] = (string(possibleTree) == "#")
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}
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f.trees = append(f.trees, row)
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f.rows++
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}
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return nil
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}
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func (f *forest) toboggan(right, down int) int {
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x, y, trees := 0, 0, 0
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for y < len(f.trees)-1 {
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y = y + down
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x = x + right
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if x > (f.width - 1) {
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x = x % f.width
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}
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if f.trees[y][x] {
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trees++
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}
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}
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return trees
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}
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func PartOne() string {
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forest := forest{}
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forest.load("three/trees.txt")
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trees := forest.toboggan(3, 1)
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return fmt.Sprintf("Found %d trees on right 3, down 1", trees)
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}
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func PartTwo() string {
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forest := forest{}
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forest.load("three/trees.txt")
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product := forest.toboggan(1, 1) *
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forest.toboggan(3, 1) *
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forest.toboggan(5, 1) *
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forest.toboggan(7, 1) *
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forest.toboggan(1, 2)
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return fmt.Sprintf("Found product %d of trees over 5 runs", product)
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}
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