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https://github.com/peter-tanner/advent-of-code-2022.git
synced 2024-11-30 06:10:22 +08:00
day 9
i learnt more about how memory safety in rust works and why we need to split a vector when mutating it in two locations to ensure they don't conflict. makes a lot of sense to me now. also learnt that tuples can be used in `match`, makes stuff really clean.
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@ -1,3 +1,123 @@
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use std::{collections::HashSet, fs::read_to_string};
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const PATH: &str = "src/input";
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fn main() {
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println!("Hello, world!");
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println!("PART 1 {}", rope_sim(2));
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println!("PART 2 {}", rope_sim(10));
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}
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fn rope_sim(rope_size: usize) -> usize {
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// FOR PART 1, THERE IS A SMARTER SOLUTION BUT WITH THE SIZE OF THE INPUT WE CAN DO IT WITH THE NAIVE SOLUTION.
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let binding = read_to_string(PATH).expect("Error reading file");
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assert!(binding.is_ascii());
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let data = binding.trim().split('\n').into_iter();
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// WTF IS THIS???
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let mut rope = Vec::<(i32, i32)>::new();
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for _ in 0..rope_size {
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rope.push((0, 0));
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}
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let mut tail_points = HashSet::<(i32, i32)>::new();
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tail_points.insert(*rope.last().unwrap());
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for instruction in data {
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let mut tokens = instruction.split_ascii_whitespace().into_iter();
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let dir = tokens.next().unwrap();
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let mag = tokens.next().unwrap().parse::<usize>().unwrap();
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for _ in 0..mag {
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// println!("({},{}), ({},{})", v_t.0, v_t.1, v_h.0, v_h.1);
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move_head(rope.get_mut(0).unwrap(), dir);
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for rope_part_i in 1..rope_size {
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// SEGMENT HEAD AND TAIL.
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let (part_1, part_2) = rope.split_at_mut(rope_part_i);
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let v_dh = part_1.get_mut(rope_part_i - 1).unwrap(); //rope.get_mut(rope_part_i - 1).unwrap()
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let v_dt = part_2.get_mut(0).unwrap(); //rope.get_mut(rope_part_i).unwrap()
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rule_1(&v_dh, v_dt);
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rule_2(&v_dh, v_dt);
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}
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tail_points.insert(*rope.last().unwrap());
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}
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// print_grid(12, &mut tail_points);
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}
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return tail_points.len();
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}
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fn move_head(v_h: &mut (i32, i32), dir: &str) {
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let dir_p = dir.chars().nth(0).unwrap();
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match dir_p {
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'U' => v_h.1 -= 1,
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'D' => v_h.1 += 1,
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'L' => v_h.0 -= 1,
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'R' => v_h.0 += 1,
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_ => {
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panic!()
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}
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};
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}
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fn rule_1(v_h: &(i32, i32), v_t: &mut (i32, i32)) {
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let di = v_h.0 - v_t.0;
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let dj = v_h.1 - v_t.1;
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let change = match (di, dj) {
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(2, 0) => (1, 0),
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(0, 2) => (0, 1),
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(-2, 0) => (-1, 0),
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(0, -2) => (0, -1),
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_ => (0, 0),
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};
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v_t.0 += change.0;
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v_t.1 += change.1;
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}
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fn rule_2(v_h: &(i32, i32), v_t: &mut (i32, i32)) {
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let di = v_h.0 - v_t.0;
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let dj = v_h.1 - v_t.1;
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let change: (i32, i32) = match (di, dj) {
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(1, 2) => (1, 1),
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(2, 1) => (1, 1),
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(2, 2) => (1, 1),
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(-2, -1) => (-1, -1),
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(-1, -2) => (-1, -1),
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(-2, -2) => (-1, -1),
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(1, -2) => (1, -1),
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(2, -1) => (1, -1),
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(2, -2) => (1, -1),
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(-1, 2) => (-1, 1),
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(-2, 1) => (-1, 1),
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(-2, 2) => (-1, 1),
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_ => (0, 0),
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};
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v_t.0 += change.0;
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v_t.1 += change.1;
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}
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fn print_grid(
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r: i32,
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tail_points: &mut HashSet<(i32, i32)>,
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// v_h: &(i32, i32),
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// v_t: &mut (i32, i32),
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) {
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for j in -r..r {
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for i in -r..r {
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if i == 0 && j == 0 {
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print!("S");
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// } else if i == v_h.0 && j == v_h.1 {
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// print!("H")
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// } else if i == v_t.0 && j == v_t.1 {
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// print!("T")
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} else if tail_points.contains(&(i, j)) {
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print!("X");
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} else {
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print!("-");
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}
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}
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println!();
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}
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}
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121
day_9/src/main_pt1.rs
Normal file
121
day_9/src/main_pt1.rs
Normal file
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@ -0,0 +1,121 @@
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use std::{collections::HashSet, fs::read_to_string};
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fn parse_direction(dir: &str, mag: &str) -> (i32, i32) {
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let dir_p = dir.chars().nth(0).unwrap();
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let mag_p = mag.parse::<i32>().unwrap();
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let v = match dir_p {
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'U' => (0, -mag_p),
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'D' => (0, mag_p),
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'L' => (-mag_p, 0),
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'R' => (mag_p, 0),
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_ => {
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panic!()
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}
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};
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return v;
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}
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fn move_head(v_h: &mut (i32, i32), dir: &str) {
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let dir_p = dir.chars().nth(0).unwrap();
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match dir_p {
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'U' => v_h.1 -= 1,
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'D' => v_h.1 += 1,
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'L' => v_h.0 -= 1,
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'R' => v_h.0 += 1,
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_ => {
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panic!()
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}
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};
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}
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fn rule_1(v_h: &(i32, i32), v_t: &mut (i32, i32)) {
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let di = v_h.0 - v_t.0;
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let dj = v_h.1 - v_t.1;
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let change = match (di, dj) {
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(2, 0) => (1, 0),
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(0, 2) => (0, 1),
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(-2, 0) => (-1, 0),
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(0, -2) => (0, -1),
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_ => (0, 0),
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};
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v_t.0 += change.0;
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v_t.1 += change.1;
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}
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fn rule_2(v_h: &(i32, i32), v_t: &mut (i32, i32)) {
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let di = v_h.0 - v_t.0;
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let dj = v_h.1 - v_t.1;
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let change: (i32, i32) = match (di, dj) {
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(1, 2) => (1, 1),
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(2, 1) => (1, 1),
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(-2, -1) => (-1, -1),
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(-1, -2) => (-1, -1),
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(1, -2) => (1, -1),
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(2, -1) => (1, -1),
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(-1, 2) => (-1, 1),
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(-2, 1) => (-1, 1),
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_ => (0, 0),
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};
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v_t.0 += change.0;
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v_t.1 += change.1;
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}
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fn print_grid(
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r: i32,
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tail_points: &mut HashSet<(i32, i32)>,
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v_h: &(i32, i32),
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v_t: &mut (i32, i32),
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) {
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for j in -r..r {
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for i in -r..r {
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if i == 0 && j == 0 {
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print!("S");
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// } else if i == v_h.0 && j == v_h.1 {
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// print!("H")
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// } else if i == v_t.0 && j == v_t.1 {
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// print!("T")
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} else if tail_points.contains(&(i, j)) {
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print!("X");
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} else {
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print!("-");
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}
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}
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println!();
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}
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}
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const PATH: &str = "src/input";
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fn main() {
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// FOR PART 1, THERE IS A SMARTER SOLUTION BUT WITH THE SIZE OF THE INPUT WE CAN DO IT WITH THE NAIVE SOLUTION.
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let mut tail_points = HashSet::<(i32, i32)>::new();
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let binding = read_to_string(PATH).expect("Error reading file");
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assert!(binding.is_ascii());
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let data = binding.trim().split('\n').into_iter();
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let v_h = &mut (0, 0);
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let v_t = &mut (0, 0);
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for instruction in data {
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let mut tokens = instruction.split_ascii_whitespace().into_iter();
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let dir = tokens.next().unwrap();
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let mag = tokens.next().unwrap().parse::<usize>().unwrap();
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// println!("{} {}", dir, mag);
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tail_points.insert(*v_t);
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for i in 0..mag {
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// println!("({},{}), ({},{})", v_t.0, v_t.1, v_h.0, v_h.1);
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move_head(v_h, dir);
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rule_1(v_h, v_t);
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rule_2(v_h, v_t);
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tail_points.insert(*v_t);
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}
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}
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print_grid(5, &mut tail_points, v_h, v_t);
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println!("PART 1 {}", tail_points.len());
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}
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