38 lines
884 B
Rust
38 lines
884 B
Rust
enum Direction {
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Forward,
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Backward,
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}
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fn main() {
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let stdin = std::io::stdin();
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let mut part1 = 0;
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let mut part2 = 0;
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for line in stdin.lines() {
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let line = line.unwrap();
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let history = line.split(" ").map(|e| e.parse().unwrap()).collect();
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part1 += extrapolate(&history, Direction::Forward);
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part2 += extrapolate(&history, Direction::Backward);
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}
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println!("{}", part1);
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println!("{}", part2);
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}
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fn extrapolate(history: &Vec<isize>, direction: Direction) -> isize {
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if history.iter().all(|e| *e == 0) {
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return 0;
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}
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let new_history = history.windows(2).map(|pair| pair[1] - pair[0]).collect();
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if let Direction::Forward = direction {
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return history.last().unwrap() + extrapolate(&new_history, direction);
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}
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return history[0] - extrapolate(&new_history, direction);
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}
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