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72 lines
1.4 KiB
Go
72 lines
1.4 KiB
Go
package day24
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import (
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"strings"
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"gitea.paas.celticinfo.fr/oabrivard/aoc2023/utils"
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)
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type Hailstone struct {
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px, py, pz, vx, vy, vz int64
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}
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type Line struct {
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m, b float64
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}
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func getLine(h Hailstone) Line {
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y2 := h.py + h.vy
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x2 := h.px + h.vx
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m := float64((y2 - h.py)) / float64((x2 - h.px))
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b := float64(y2) - m*float64(x2)
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return Line{m, b}
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}
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func crossCoord(h1, h2 Hailstone) (bool, float64, float64) {
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l1 := getLine(h1)
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l2 := getLine(h2)
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if l1.m == l2.m {
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return false, -1, -1
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}
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x := (l2.b - l1.b) / (l1.m - l2.m)
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y := l2.m*x + l2.b
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if h1.px > int64(x) && h1.vx >= 0 || h1.px < int64(x) && h1.vx <= 0 {
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return false, -1, -1
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}
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if h2.px > int64(x) && h2.vx >= 0 || h2.px < int64(x) && h2.vx <= 0 {
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return false, -1, -1
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}
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return true, x, y
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}
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func Part1(lines []string, min, max float64) int {
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stones := []Hailstone{}
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for _, line := range lines {
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values := utils.ParseInt64Array(strings.Replace(line, " @", ",", -1), ", ")
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stone := Hailstone{values[0], values[1], values[2], values[3], values[4], values[5]}
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stones = append(stones, stone)
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}
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result := 0
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for i := range stones {
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for j := i + 1; j < len(stones); j++ {
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areCrossing, x, y := crossCoord(stones[i], stones[j])
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if !areCrossing {
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continue
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}
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if x >= min && y >= min && x <= max && y <= max {
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result++
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}
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//fmt.Println("x : ", x, ", y : ", y)
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}
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}
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return result
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}
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