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d2 (one of the part 2 solutions is wrong)
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,6 @@ | ||
| 7 6 4 2 1 | ||
| 1 2 7 8 9 | ||
| 9 7 6 2 1 | ||
| 1 3 2 4 5 | ||
| 8 6 4 4 1 | ||
| 1 3 6 7 9 |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,126 @@ | ||
| use std::fmt; | ||
|
|
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| use itertools::Itertools; | ||
|
|
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| use crate::Parse; | ||
|
|
||
| #[derive(Clone)] | ||
| pub struct Input(Vec<Line>); | ||
|
|
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| #[derive(Clone)] | ||
| struct Line(Vec<u32>); | ||
|
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| impl Parse for Input { | ||
| fn parse(input: &str) -> Self { | ||
| Self( | ||
| input | ||
| .lines() | ||
| .map(|line| Line(line.split(' ').map(|s| s.parse::<u32>().unwrap()).collect())) | ||
| .collect(), | ||
| ) | ||
| } | ||
| } | ||
|
|
||
| #[derive(Debug, Clone, Copy, PartialEq, Eq)] | ||
| enum Direction { | ||
| Increase, | ||
| Decrease, | ||
| Illegal, | ||
| } | ||
|
|
||
| fn compare(left: u32, right: u32) -> Direction { | ||
| if (right + 1..=right + 3).contains(&left) { | ||
| Direction::Decrease | ||
| } else if (left + 1..=left + 3).contains(&right) { | ||
| Direction::Increase | ||
| } else { | ||
| Direction::Illegal | ||
| } | ||
| } | ||
|
|
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| fn is_safe_windows(levels: impl Iterator<Item = u32>) -> bool { | ||
| let directions = levels.tuple_windows().map(|(left, right)| compare(left, right)); | ||
| directions.tuple_windows().all(|(left, right)| left != Direction::Illegal && left == right) | ||
| } | ||
|
|
||
| fn is_safe_first_all(levels: impl Iterator<Item = u32>) -> bool { | ||
| let mut directions = levels.tuple_windows().map(|(left, right)| compare(left, right)); | ||
| let first = directions.next().unwrap(); | ||
| first != Direction::Illegal && directions.all(|d| d == first) | ||
| } | ||
|
|
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| pub fn p1_windows(input: Input) -> impl fmt::Display { | ||
| fn is_safe(line: &Line) -> bool { is_safe_windows(line.0.iter().copied()) } | ||
|
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| input.0.iter().filter(|line| is_safe(line)).count() | ||
| } | ||
|
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| pub fn p1_first_all(input: Input) -> impl fmt::Display { | ||
| fn is_safe(line: &Line) -> bool { is_safe_first_all(line.0.iter().copied()) } | ||
|
|
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| input.0.iter().filter(|line| is_safe(line)).count() | ||
| } | ||
|
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| pub fn p2_brute_force(input: Input) -> impl fmt::Display { | ||
| fn is_safe(line: &Line) -> bool { | ||
| is_safe_first_all(line.0.iter().copied()) | ||
| || (0..line.0.len()).any(|skip| { | ||
| is_safe_first_all( | ||
| line.0[..skip].iter().copied().chain(line.0[skip + 1..].iter().copied()), | ||
| ) | ||
| }) | ||
| } | ||
|
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| input.0.iter().filter(|line| is_safe(line)).count() | ||
| } | ||
|
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| // TODO: this answer is wrong | ||
| pub fn p2_vec(input: Input) -> impl fmt::Display { | ||
| fn is_safe_skip(line: &Line, index: usize, dominant: Direction) -> bool { | ||
| if let (Some(prev_index), Some(&next_level)) = (index.checked_sub(1), line.0.get(index + 1)) | ||
| { | ||
| if compare(line.0[prev_index], next_level) != dominant { | ||
| return false; | ||
| } | ||
| } | ||
|
|
||
| true | ||
| } | ||
|
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| fn is_safe(line: &Line) -> bool { | ||
| let directions: Vec<_> = | ||
| line.0.iter().tuple_windows().map(|(&left, &right)| compare(left, right)).collect(); | ||
|
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||
| let increase_count = directions.iter().filter(|&&d| d == Direction::Increase).count(); | ||
| let dominants = if increase_count * 2 > directions.len() { | ||
| &[Direction::Increase][..] | ||
| } else if increase_count * 2 == directions.len() { | ||
| &[Direction::Increase, Direction::Decrease][..] | ||
| } else { | ||
| &[Direction::Decrease][..] | ||
| }; | ||
|
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||
| dominants.iter().any(|&dominant| { | ||
| let mut violations = directions.iter().enumerate().filter(|(_, &d)| d != dominant); | ||
| if let Some((index, _)) = violations.next() { | ||
| // line[index] -> line[index+1] violation, | ||
| // attempt to skip either line[index] or line[index+1] | ||
|
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||
| if is_safe_skip(line, index, dominant) && is_safe_skip(line, index + 1, dominant) { | ||
| let mut next_violation = violations.next(); | ||
| if next_violation.is_some_and(|(next_index, _)| next_index == index + 1) { | ||
| next_violation = violations.next(); | ||
| } | ||
|
|
||
| next_violation.is_none() | ||
| } else { | ||
| false | ||
| } | ||
| } else { | ||
| true | ||
| } | ||
| }) | ||
| } | ||
|
|
||
| input.0.iter().filter(|line| is_safe(line)).count() | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,4 +1,3 @@ | ||
| mod all; | ||
| pub use all::bench; | ||
| pub use all::run; | ||
| use all::Parse; | ||
| pub use all::{bench, run}; |