2022 Day 9 Complete!

This commit is contained in:
Brian Buller 2022-12-09 09:03:12 -06:00
parent 30b00e68a4
commit f5270a396a
6 changed files with 2503 additions and 0 deletions

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2022/day09/input Normal file

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package main
import (
"fmt"
"os"
"strings"
"time"
h "git.bullercodeworks.com/brian/adventofcode/helpers"
)
var sleepTime = (time.Second / 5)
var minx, miny, maxx, maxy int
func main() {
inp := h.StdinToStringSlice()
watch := len(os.Args) > 1 && strings.HasPrefix(os.Args[1], "-w")
if watch {
if strings.Contains(os.Args[1], "=") {
pts := strings.Split(os.Args[1], "=")
sleepTime = (time.Second / time.Duration(h.Atoi(pts[1])))
}
}
simulate(inp, 10, watch)
}
func buildInstructions(inp []string) []byte {
var inst []byte
for i := range inp {
dir, count := inp[i][0], h.Atoi(inp[i][2:])
for j := 0; j < count; j++ {
inst = append(inst, dir)
}
}
return inst
}
func simulate(inp []string, knotCount int, watch bool) {
if watch {
fmt.Print(h.CLEAR_SCREEN)
}
visited := make(map[h.Coordinate]bool)
inst := buildInstructions(inp)
var knots []h.Coordinate
for i := 0; i < knotCount; i++ {
knots = append(knots, h.Coordinate{X: 0, Y: 0})
}
if watch {
fmt.Println("# Part 1")
printVisits(visited, knots)
}
for i, dir := range inst {
moveHead(dir, knots)
visited[knots[len(knots)-1]] = true
if watch {
time.Sleep(sleepTime)
fmt.Print(h.CLEAR_SCREEN)
fmt.Printf("# Part 1 (%d/%d)\n", i, len(inst))
printVisits(visited, knots)
}
}
if watch {
time.Sleep(sleepTime)
fmt.Print(h.CLEAR_SCREEN)
}
fmt.Println("# Part 1")
if watch {
printVisits(visited, knots)
}
fmt.Printf("Tail visited %d positions\n", len(visited))
}
func moveHead(dir byte, knots []h.Coordinate) {
prevKnots := make([]h.Coordinate, len(knots))
copy(prevKnots, knots)
switch dir {
case 'U':
knots[0] = knots[0].North()
case 'R':
knots[0] = knots[0].East()
case 'D':
knots[0] = knots[0].South()
case 'L':
knots[0] = knots[0].West()
}
if knots[0].X < minx {
minx = knots[0].X
}
if knots[0].X > maxx {
maxx = knots[0].X
}
if knots[0].Y < miny {
miny = knots[0].Y
}
if knots[0].Y > maxy {
maxy = knots[0].Y
}
for i := 1; i < len(knots); i++ {
// Go through all knots and check if any need to move
if !knots[i].Equals(knots[i-1]) && !knots[i].Adjacent(knots[i-1]) {
if knots[i].X == knots[i-1].X {
// Same column
if knots[i].Y < knots[i-1].Y {
knots[i].Y++
} else {
knots[i].Y--
}
} else if knots[i].Y == knots[i-1].Y {
// Save row
if knots[i].X < knots[i-1].X {
knots[i].X++
} else {
knots[i].X--
}
} else {
// Not in the same row or column
if knots[i].X < knots[i-1].X {
knots[i].X++
} else {
knots[i].X--
}
if knots[i].Y < knots[i-1].Y {
knots[i].Y++
} else {
knots[i].Y--
}
}
} else {
// If one knot didn't need to move, none behind it will
break
}
}
}
func printVisits(m map[h.Coordinate]bool, knots []h.Coordinate) {
for y := miny; y <= maxy; y++ {
for x := minx; x <= maxx; x++ {
var isKnot bool
for i := range knots {
if knots[i].X == x && knots[i].Y == y {
isKnot = true
var bt byte
if i == 0 {
bt = 'H'
} else {
bt = '0' + byte(i)
}
fmt.Print(string(bt))
break
}
}
if !isKnot {
if v, ok := m[h.Coordinate{X: x, Y: y}]; ok && v {
fmt.Print("#")
} else {
fmt.Print(".")
}
}
}
fmt.Println()
}
fmt.Printf("Bridge: %s\n", knots)
fmt.Println()
}

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2022/day09/problem Normal file
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Advent of Code
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--- Day 9: Rope Bridge ---
This rope bridge creaks as you walk along it. You aren't sure how old it is, or whether it can even support your weight.
It seems to support the Elves just fine, though. The bridge spans a gorge which was carved out by the massive river far
below you.
You step carefully; as you do, the ropes stretch and twist. You decide to distract yourself by modeling rope physics;
maybe you can even figure out where not to step.
Consider a rope with a knot at each end; these knots mark the head and the tail of the rope. If the head moves far
enough away from the tail, the tail is pulled toward the head.
Due to nebulous reasoning involving Planck lengths, you should be able to model the positions of the knots on a
two-dimensional grid. Then, by following a hypothetical series of motions (your puzzle input) for the head, you can
determine how the tail will move.
Due to the aforementioned Planck lengths, the rope must be quite short; in fact, the head (H) and tail (T) must always
be touching (diagonally adjacent and even overlapping both count as touching):
....
.TH.
....
....
.H..
..T.
....
...
.H. (H covers T)
...
If the head is ever two steps directly up, down, left, or right from the tail, the tail must also move one step in that
direction so it remains close enough:
..... ..... .....
.TH.. -> .T.H. -> ..TH.
..... ..... .....
... ... ...
.T. .T. ...
.H. -> ... -> .T.
... .H. .H.
... ... ...
Otherwise, if the head and tail aren't touching and aren't in the same row or column, the tail always moves one step
diagonally to keep up:
..... ..... .....
..... ..H.. ..H..
..H.. -> ..... -> ..T..
.T... .T... .....
..... ..... .....
..... ..... .....
..... ..... .....
..H.. -> ...H. -> ..TH.
.T... .T... .....
..... ..... .....
You just need to work out where the tail goes as the head follows a series of motions. Assume the head and the tail both
start at the same position, overlapping.
For example:
R 4
U 4
L 3
D 1
R 4
D 1
L 5
R 2
This series of motions moves the head right four steps, then up four steps, then left three steps, then down one step,
and so on. After each step, you'll need to update the position of the tail if the step means the head is no longer
adjacent to the tail. Visually, these motions occur as follows (s marks the starting position as a reference point):
== Initial State ==
......
......
......
......
H..... (H covers T, s)
== R 4 ==
......
......
......
......
TH.... (T covers s)
......
......
......
......
sTH...
......
......
......
......
s.TH..
......
......
......
......
s..TH.
== U 4 ==
......
......
......
....H.
s..T..
......
......
....H.
....T.
s.....
......
....H.
....T.
......
s.....
....H.
....T.
......
......
s.....
== L 3 ==
...H..
....T.
......
......
s.....
..HT..
......
......
......
s.....
.HT...
......
......
......
s.....
== D 1 ==
..T...
.H....
......
......
s.....
== R 4 ==
..T...
..H...
......
......
s.....
..T...
...H..
......
......
s.....
......
...TH.
......
......
s.....
......
....TH
......
......
s.....
== D 1 ==
......
....T.
.....H
......
s.....
== L 5 ==
......
....T.
....H.
......
s.....
......
....T.
...H..
......
s.....
......
......
..HT..
......
s.....
......
......
.HT...
......
s.....
......
......
HT....
......
s.....
== R 2 ==
......
......
.H.... (H covers T)
......
s.....
......
......
.TH...
......
s.....
After simulating the rope, you can count up all of the positions the tail visited at least once. In this diagram, s
again marks the starting position (which the tail also visited) and # marks other positions the tail visited:
..##..
...##.
.####.
....#.
s###..
So, there are 13 positions the tail visited at least once.
Simulate your complete hypothetical series of motions. How many positions does the tail of the rope visit at least once?
To begin, get your puzzle input.
Answer: _____________________ [ [Submit] ]
You can also [Shareon Twitter Mastodon] this puzzle.
References
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. Advent of Code Supporter
https://adventofcode.com/2022/support
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. https://careers.king.com/
. https://en.wikipedia.org/wiki/Planck_units#Planck_length
. https://adventofcode.com/2022/day/9/input
. https://twitter.com/intent/tweet?text=%22Rope+Bridge%22+%2D+Day+9+%2D+Advent+of+Code+2022&url=https%3A%2F%2Fadventofcode%2Ecom%2F2022%2Fday%2F9&related=ericwastl&hashtags=AdventOfCode
. javascript:void(0);

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R 4
U 4
L 3
D 1
R 4
D 1
L 5
R 2

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2022/day09/testinput2 Normal file
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R 5
U 8
L 8
D 3
R 17
D 10
L 25
U 20

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@ -97,3 +97,13 @@ func (c Coordinate) Distance(t Coordinate) int {
func (c Coordinate) Equals(c2 Coordinate) bool {
return c.X == c2.X && c.Y == c2.Y
}
func (c Coordinate) Adjacent(c2 Coordinate) bool {
return c2.Equals(c.North()) ||
c2.Equals(c.NE()) ||
c2.Equals(c.East()) ||
c2.Equals(c.SE()) ||
c2.Equals(c.South()) ||
c2.Equals(c.SW()) ||
c2.Equals(c.West()) ||
c2.Equals(c.NW())
}