Giter Club home page Giter Club logo

Comments (7)

simonw avatar simonw commented on June 28, 2024

Example board is 6 wide, 5 high.

But... there are values in input.txt higher than that, so assume that there's no bounds on the board.

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

Movement rules:

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:

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:

[...]

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.

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

I need to model the state of the board, then loop through each move in turn applying it to the head. After each move is applied to the head I can run code which decides if the tail should be updated or not - and logs the co-ordinates that the tail has visited so I can count them at the end.

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

I got 14 against the example. I stopped counting the starting point as somewhere visited by the tail and got the expected answer 13.

Then I tried against input.txt and got the right answer, 6339.

CORRECTION: That's because I modified example.txt to add a 1 up 1 right as a test and forgot to remove that again. You actually SHOULD count the 0, 0 square.

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

Output against example.txt:

day_09 % cargo run
   Compiling day_09 v0.1.0 (/Users/simon/Dropbox/Development/advent-of-code-2022-in-rust/day_09)
    Finished dev [unoptimized + debuginfo] target(s) in 0.49s
     Running `target/debug/day_09`
X.........
..........
..........
..........
..........
..........
..........
..........
..........
..........
direction = R distance = 4
  head_pos = (1, 0)
  Touching, no need to move
TH........
..........
..........
..........
..........
..........
..........
..........
..........
..........
  head_pos = (2, 0)
  tail_pos = (1, 0)
.TH.......
..........
..........
..........
..........
..........
..........
..........
..........
..........
  head_pos = (3, 0)
  tail_pos = (2, 0)
..TH......
..........
..........
..........
..........
..........
..........
..........
..........
..........
  head_pos = (4, 0)
  tail_pos = (3, 0)
...TH.....
..........
..........
..........
..........
..........
..........
..........
..........
..........
direction = U distance = 4
  head_pos = (4, 1)
  Diagonally touching, no need to move
...T......
....H.....
..........
..........
..........
..........
..........
..........
..........
..........
  head_pos = (4, 2)
  tail_pos = (4, 1)
..........
....T.....
....H.....
..........
..........
..........
..........
..........
..........
..........
  head_pos = (4, 3)
  tail_pos = (4, 2)
..........
..........
....T.....
....H.....
..........
..........
..........
..........
..........
..........
  head_pos = (4, 4)
  tail_pos = (4, 3)
..........
..........
..........
....T.....
....H.....
..........
..........
..........
..........
..........
direction = L distance = 3
  head_pos = (3, 4)
  Diagonally touching, no need to move
..........
..........
..........
....T.....
...H......
..........
..........
..........
..........
..........
  head_pos = (2, 4)
  tail_pos = (3, 4)
..........
..........
..........
..........
..HT......
..........
..........
..........
..........
..........
  head_pos = (1, 4)
  tail_pos = (2, 4)
..........
..........
..........
..........
.HT.......
..........
..........
..........
..........
..........
direction = D distance = 1
  head_pos = (1, 3)
  Diagonally touching, no need to move
..........
..........
..........
.H........
..T.......
..........
..........
..........
..........
..........
direction = R distance = 4
  head_pos = (2, 3)
  Touching, no need to move
..........
..........
..........
..H.......
..T.......
..........
..........
..........
..........
..........
  head_pos = (3, 3)
  Diagonally touching, no need to move
..........
..........
..........
...H......
..T.......
..........
..........
..........
..........
..........
  head_pos = (4, 3)
  tail_pos = (3, 3)
..........
..........
..........
...TH.....
..........
..........
..........
..........
..........
..........
  head_pos = (5, 3)
  tail_pos = (4, 3)
..........
..........
..........
....TH....
..........
..........
..........
..........
..........
..........
direction = D distance = 1
  head_pos = (5, 2)
  Diagonally touching, no need to move
..........
..........
.....H....
....T.....
..........
..........
..........
..........
..........
..........
direction = L distance = 5
  head_pos = (4, 2)
  Touching, no need to move
..........
..........
....H.....
....T.....
..........
..........
..........
..........
..........
..........
  head_pos = (3, 2)
  Diagonally touching, no need to move
..........
..........
...H......
....T.....
..........
..........
..........
..........
..........
..........
  head_pos = (2, 2)
  tail_pos = (3, 2)
..........
..........
..HT......
..........
..........
..........
..........
..........
..........
..........
  head_pos = (1, 2)
  tail_pos = (2, 2)
..........
..........
.HT.......
..........
..........
..........
..........
..........
..........
..........
  head_pos = (0, 2)
  tail_pos = (1, 2)
..........
..........
HT........
..........
..........
..........
..........
..........
..........
..........
direction = R distance = 2
  head_pos = (1, 2)
  tail_pos = (1, 2)
..........
..........
.X........
..........
..........
..........
..........
..........
..........
..........
  head_pos = (2, 2)
  Touching, no need to move
..........
..........
.TH.......
..........
..........
..........
..........
..........
..........
..........
tail_visited = [(0, 0), (1, 0), (2, 0), (3, 0), (4, 1), (4, 2), (4, 3), (3, 4), (2, 4), (3, 3), (4, 3), (3, 2), (2, 2), (1, 2), (1, 2)]
Number of unique locations = 13

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

Part 2:

Rather than two knots, you now must simulate a rope consisting of ten knots. One knot is still the head of the rope and moves according to the series of motions. Each knot further down the rope follows the knot in front of it using the same rules as before.

Simulate your complete series of motions on a larger rope with ten knots. How many positions does the tail of the rope visit at least once?

from advent-of-code-2022-in-rust.

simonw avatar simonw commented on June 28, 2024

Got it to work against the larger example AND got the right result for my input - 2541.

I modified the original script without creating a backup, so now my solution to part 1 lives on in version control:

advent-of-code-2022-in-rust/day_09/src/main.rs

Lines 1 to 98 in b46f205

use std::fs;
fn main() {
let file_contents = fs::read_to_string("input.txt").unwrap();
let mut head_pos: (i32, i32) = (0, 0);
let mut tail_pos: (i32, i32) = (0, 0);
let mut tail_visited = Vec::new();
tail_visited.push(tail_pos);
print_board(&head_pos, &tail_pos);
for line in file_contents.lines() {
// Line is "R 4" - split into move, distance (integer)
let mut parts = line.split(" ");
let direction = parts.next().unwrap();
let distance = parts.next().unwrap().parse::<i32>().unwrap();
println!("direction = {} distance = {}", direction, distance);
// First move the head
for _ in 0..distance {
match direction {
"R" => head_pos.0 += 1,
"L" => head_pos.0 -= 1,
"U" => head_pos.1 += 1,
"D" => head_pos.1 -= 1,
_ => panic!("Unknown direction {}", direction),
}
println!(" head_pos = {:?}", head_pos);
// Now move the tail, if it needs to be moved
// Is tail within one of head in either direction?
if (head_pos.0 == tail_pos.0 && (head_pos.1 - tail_pos.1).abs() == 1)
|| (head_pos.1 == tail_pos.1 && (head_pos.0 - tail_pos.0).abs() == 1)
{
println!(" Touching, no need to move");
}
// Are tail and head diagonally touching?
else if (head_pos.0 - tail_pos.0).abs() == 1 && (head_pos.1 - tail_pos.1).abs() == 1 {
println!(" Diagonally touching, no need to move");
} else {
// Need to move the tail
// If tail is not in same row AND column as head...
if head_pos.0 != tail_pos.0 && head_pos.1 != tail_pos.1 {
// Move it diagonally in the right direction
tail_pos.0 += to_one(head_pos.0 - tail_pos.0);
tail_pos.1 += to_one(head_pos.1 - tail_pos.1);
} else {
// Move it in the right direction
if head_pos.0 == tail_pos.0 {
tail_pos.1 += to_one(head_pos.1 - tail_pos.1);
} else {
tail_pos.0 += to_one(head_pos.0 - tail_pos.0);
}
}
println!(" tail_pos = {:?}", tail_pos);
tail_visited.push(tail_pos);
}
print_board(&head_pos, &tail_pos);
}
}
println!("tail_visited = {:?}", tail_visited);
// Count unique tuples in that
let mut unique_tuples = Vec::new();
for tuple in tail_visited {
if !unique_tuples.contains(&tuple) {
unique_tuples.push(tuple);
}
}
println!("Number of unique locations = {:?}", unique_tuples.len());
}
fn print_board(head_pos: &(i32, i32), tail_pos: &(i32, i32)) {
for y in 0..10 {
for x in 0..10 {
// If both in same spot do an X
if x == head_pos.0 && y == head_pos.1 && x == tail_pos.0 && y == tail_pos.1 {
print!("X");
} else if x == head_pos.0 && y == head_pos.1 {
print!("H");
} else if x == tail_pos.0 && y == tail_pos.1 {
print!("T");
} else {
print!(".");
}
}
println!("");
}
}
fn to_one(n: i32) -> i32 {
if n > 0 {
1
} else if n < 0 {
-1
} else {
0
}
}

Here's my part 2 solution:

advent-of-code-2022-in-rust/day_09/src/main.rs

Lines 1 to 108 in 58aae1d

use std::fs;
fn main() {
let file_contents = fs::read_to_string("input.txt").unwrap();
let mut knots: Vec<(i32, i32)> = Vec::new();
for _ in 0..10 {
knots.push((0, 0));
}
let mut tail_visited: Vec<(i32, i32)> = Vec::new();
tail_visited.push((0, 0));
// print_board(&knots);
for line in file_contents.lines() {
// Line is "R 4" - split into move, distance (integer)
let mut parts = line.split(" ");
let direction = parts.next().unwrap();
let distance = parts.next().unwrap().parse::<i32>().unwrap();
println!("direction = {} distance = {}", direction, distance);
// First move the head
for _ in 0..distance {
match direction {
"R" => knots[0].0 += 1,
"L" => knots[0].0 -= 1,
"U" => knots[0].1 += 1,
"D" => knots[0].1 -= 1,
_ => panic!("Unknown direction {}", direction),
}
println!(" head_pos = {:?}", knots[0]);
// Now move each other knot in turn, if it needs to be moved
for i in 1..knots.len() {
// Is knot within one of head in either direction?
let mut knot = knots[i];
let prev = knots[i - 1];
if (prev.0 == knot.0 && (prev.1 - knot.1).abs() == 1)
|| (prev.1 == knot.1 && (prev.0 - knot.0).abs() == 1)
{
println!(" Touching, no need to move");
}
// Are tail and head diagonally touching?
else if (prev.0 - knot.0).abs() == 1 && (prev.1 - knot.1).abs() == 1 {
println!(" Diagonally touching, no need to move");
} else {
// Need to move the tail
// If tail is not in same row AND column as head...
if prev.0 != knot.0 && prev.1 != knot.1 {
// Move it diagonally in the right direction
knot.0 += to_one(prev.0 - knot.0);
knot.1 += to_one(prev.1 - knot.1);
} else {
// Move it in the right direction
if prev.0 == knot.0 {
knot.1 += to_one(prev.1 - knot.1);
} else {
knot.0 += to_one(prev.0 - knot.0);
}
}
knots[i] = knot;
println!(" knot = {:?}", knot);
if i == 9 {
tail_visited.push(knot);
}
}
}
// print_board(&head_pos, &tail_pos);
}
}
println!("tail_visited = {:?}", tail_visited);
// Count unique tuples in that
let mut unique_tuples = Vec::new();
for tuple in tail_visited {
if !unique_tuples.contains(&tuple) {
unique_tuples.push(tuple);
}
}
println!("Number of unique locations = {:?}", unique_tuples.len());
}
/*
fn print_board(knots: &knot) {
for y in 0..10 {
for x in 0..10 {
// If both in same spot do an X
if x == head_pos.0 && y == head_pos.1 && x == tail_pos.0 && y == tail_pos.1 {
print!("X");
} else if x == head_pos.0 && y == head_pos.1 {
print!("H");
} else if x == tail_pos.0 && y == tail_pos.1 {
print!("T");
} else {
print!(".");
}
}
println!("");
}
}
*/
fn to_one(n: i32) -> i32 {
if n > 0 {
1
} else if n < 0 {
-1
} else {
0
}
}

from advent-of-code-2022-in-rust.

Related Issues (17)

Recommend Projects

  • React photo React

    A declarative, efficient, and flexible JavaScript library for building user interfaces.

  • Vue.js photo Vue.js

    🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.

  • Typescript photo Typescript

    TypeScript is a superset of JavaScript that compiles to clean JavaScript output.

  • TensorFlow photo TensorFlow

    An Open Source Machine Learning Framework for Everyone

  • Django photo Django

    The Web framework for perfectionists with deadlines.

  • D3 photo D3

    Bring data to life with SVG, Canvas and HTML. 📊📈🎉

Recommend Topics

  • javascript

    JavaScript (JS) is a lightweight interpreted programming language with first-class functions.

  • web

    Some thing interesting about web. New door for the world.

  • server

    A server is a program made to process requests and deliver data to clients.

  • Machine learning

    Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.

  • Game

    Some thing interesting about game, make everyone happy.

Recommend Org

  • Facebook photo Facebook

    We are working to build community through open source technology. NB: members must have two-factor auth.

  • Microsoft photo Microsoft

    Open source projects and samples from Microsoft.

  • Google photo Google

    Google ❤️ Open Source for everyone.

  • D3 photo D3

    Data-Driven Documents codes.