From 2e01de882d978dcc1f03b97b479ebd7a4a095aa4 Mon Sep 17 00:00:00 2001 From: Brian Buller Date: Thu, 28 Dec 2023 09:15:31 -0600 Subject: [PATCH] Leaving Code & Coffee --- 2023/day24/main.go | 80 ++++++++++++++++++++++++++++++++++++++++++++ 2023/day24/testinput | 5 +++ 2 files changed, 85 insertions(+) create mode 100644 2023/day24/testinput diff --git a/2023/day24/main.go b/2023/day24/main.go index 7146225..7a81ffd 100644 --- a/2023/day24/main.go +++ b/2023/day24/main.go @@ -14,9 +14,89 @@ func main() { } func part1(inp []string) { + //testMin, testMax := float64(7), float64(27) // Test Input + testMin, testMax := float64(200000000000000), float64(400000000000000) + var all []*hailstone + for _, i := range inp { + all = append(all, NewHailstone(i)) + } + var count int + for i := 0; i < len(all)-1; i++ { + for j := i + 1; j < len(all); j++ { + x, y := findIntersection(all[i], all[j]) + if x >= testMin && x <= testMax && y >= testMin && y <= testMax { + count++ + } + } + } + fmt.Println("# Part 1") + fmt.Println(count) } func part2(inp []string) { + var all []*hailstone + for _, i := range inp { + all = append(all, NewHailstone(i)) + } fmt.Println("# Part 2") + fmt.Println(findThrow(all)) +} + +// https://github.com/rumkugel13/AdventOfCode2023/blob/main/day24.go#L139 +func findThrow(all []*hailstone) int { + maybeX, maybeY, maybeZ := []int{}, []int{}, []int{} + for i := 0; i < len(all)-1; i++ { + for j := i + 1; j < len(all); j++ { + a, b := all[i], all[j] + if a.DX == b.DX { + nextMaybe := findMatchingVelocity(int(b.X-a.X), int(a.DX)) + } + } + } +} +func findMatchingVelocity(diff, vel int) []int { + match := []int{} + for v := -1000; v < 1000; v++ { + if v != vel && diff%(v-vel) == 0 { + match = append(match, v) + } + } + return match +} + +func slope(h *hailstone) float64 { + return h.DY / h.DX +} + +func findIntersection(i, j *hailstone) (float64, float64) { + if slope(i) == slope(j) { + return -1, -1 + } + cx := (j.Y - (j.DY/j.DX)*j.X - (i.Y - (i.DY/i.DX)*i.X)) / (i.DY/i.DX - j.DY/j.DX) + perp := !((cx > i.X) == (i.DX > 0) && (cx > j.X) == (j.DX > 0)) + if perp { + return -1, -1 + } + + y := ((-i.DY/j.DY)*(j.X*j.DY-j.Y*j.DX) + i.X*i.DY - i.Y*i.DX) / ((j.DX * i.DY / j.DY) - i.DX) + x := y*j.DX/j.DY + (j.X*j.DY-j.Y*j.DX)/j.DY + return x, y +} + +type hailstone struct { + X, Y, Z float64 + DX, DY, DZ float64 +} + +func NewHailstone(inp string) *hailstone { + h := hailstone{} + fmt.Sscanf(inp, "%f, %f, %f @ %f, %f, %f", + &h.X, &h.Y, &h.Z, &h.DX, &h.DY, &h.DZ) + return &h +} + +func (h hailstone) String() string { + return fmt.Sprintf("%f, %f, %f @ %f, %f, %f", + h.X, h.Y, h.Z, h.DX, h.DY, h.DZ) } diff --git a/2023/day24/testinput b/2023/day24/testinput new file mode 100644 index 0000000..35963dc --- /dev/null +++ b/2023/day24/testinput @@ -0,0 +1,5 @@ +19, 13, 30 @ -2, 1, -2 +18, 19, 22 @ -1, -1, -2 +20, 25, 34 @ -2, -2, -4 +12, 31, 28 @ -1, -2, -1 +20, 19, 15 @ 1, -5, -3