81 lines
1.9 KiB
Rust
81 lines
1.9 KiB
Rust
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use advent_of_code_2024::{make_main, SResult};
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make_main!();
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// CODE
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#[derive(PartialEq, Clone, Copy)]
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enum Direction {
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Up,
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Down,
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}
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impl Direction {
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fn from(a: usize, b: usize) -> Self {
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if a > b {
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Direction::Down
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} else {
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Direction::Up
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}
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}
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}
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fn solve(lines: Vec<String>) -> SResult<usize> {
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let mut fail_count = 0;
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for line in lines.iter() {
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let reports: Vec<usize> = line
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.split_whitespace()
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.map(|v| v.parse::<usize>().unwrap())
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.collect();
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let problems = match test(&reports) {
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// Cool, nothing to see here
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Ok(_) => continue,
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Err(e) => e,
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};
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let mut pass = false;
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for problem in problems {
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let mut l1 = reports.clone();
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l1.remove(problem);
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if test(&l1).is_ok() {
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pass = true;
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break;
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}
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}
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if !pass {
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fail_count += 1;
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}
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}
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Ok(lines.len() - fail_count)
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}
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// Tests the report, and returns indexes around where a failure is detected.
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fn test(reports: &[usize]) -> Result<(), Vec<usize>> {
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let mut i = 0;
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let direction = Direction::from(reports[0], reports[1]);
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while i + 1 < reports.len() {
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let delta = reports[i].abs_diff(reports[i + 1]);
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if delta < 1 || delta > 3 || direction != Direction::from(reports[i], reports[i + 1]) {
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let mut errs = vec![i, i + 1];
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if i > 0 {
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errs.push(i - 1);
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}
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return Err(errs);
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}
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i += 1;
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}
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Ok(())
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}
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// CODE
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#[cfg(test)]
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mod tests {
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use advent_of_code_2024::input;
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use super::*;
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#[test]
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fn sample_input() {
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let strings: Vec<String> = input!("d2p1.txt");
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let got = solve(strings).unwrap();
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assert_eq!(got, 4);
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}
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}
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