94 lines
2.3 KiB
Rust
94 lines
2.3 KiB
Rust
use std::fs;
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use std::iter;
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use std::str::FromStr;
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use std::collections::HashSet;
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fn main() {
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const FILE_PATH: &str = "input";
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println!("Hi this is the nineth day of AOC2022, first we will read the file {}", FILE_PATH);
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let contents = fs::read_to_string(FILE_PATH)
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.expect("Should have been able to read the file");
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println!("The ammount of visited positions are: {}", get_positions(&contents, 1).len());
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println!("The ammount of visited positions are: {}", get_positions(&contents, 9).len());
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}
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fn get_positions(input: &str, num_knots: usize) -> HashSet<(i32, i32)> {
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let moves: Vec<_> = input.lines().map(|l| {
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let l: Vec<_> = l.split(" ").collect();
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let dir = match &l[0] {
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&"U" => (0, 1),
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&"D" => (0, -1),
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&"L" => (-1, 0),
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&"R" => (1, 0),
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&_ => unreachable!()
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};
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iter::repeat(dir).take(usize::from_str(l[1]).expect("NaN"))
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}).flatten().collect();
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let mut head = (0,0);
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let mut knots = vec![(0,0); num_knots];
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let mut visited = HashSet::new();
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for m in moves {
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head = (head.0+m.0, head.1+m.1);
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knots[0] = move_tail(head, knots[0]);
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for i in 1..num_knots {
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knots[i] = move_tail(knots[i-1], knots[i]);
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}
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visited.insert(knots[num_knots-1]);
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}
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visited
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}
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fn move_tail(head: (i32, i32), tail: (i32, i32)) -> (i32, i32) {
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let dx = head.0 - tail.0;
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let dy = head.1 - tail.1;
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if dx.abs() <= 1 && dy.abs() <= 1 {return tail;}
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match (dx, dy) {
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(2,2) => (tail.0+1, tail.1+1),
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(-2,2) => (tail.0-1, tail.1+1),
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(2,-2) => (tail.0+1, tail.1-1),
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(-2,-2) => (tail.0-1, tail.1-1),
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(2,y) => (tail.0+1, tail.1+y),
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(-2,y) => (tail.0-1, tail.1+y),
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(x,2) => (tail.0+x, tail.1+1),
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(x,-2) => (tail.0+x, tail.1-1),
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_ => unreachable!()
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}
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}
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#[cfg(test)]
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mod test {
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const INPUT: &str = r#"R 4
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U 4
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L 3
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D 1
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R 4
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D 1
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L 5
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R 2"#;
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const INPUT2: &str = r#"R 5
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U 8
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L 8
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D 3
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R 17
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D 10
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L 25
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U 20"#;
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use super::*;
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#[test]
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fn rope1() {
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assert_eq!(get_positions(INPUT, 1).len(), 13);
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}
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#[test]
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fn rope2() {
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assert_eq!(get_positions(INPUT, 9).len(), 1);
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}
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#[test]
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fn rope3() {
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assert_eq!(get_positions(INPUT2, 9).len(), 36);
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}
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} |