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60 lines
1.3 KiB
60 lines
1.3 KiB
#[test]
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fn test_day_10() {
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let mut foo = LookAndSay { seq: vec![2, 1, 1] };
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assert_eq!(vec![1, 2, 2, 1], foo.next().unwrap());
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foo = LookAndSay { seq: vec![1] };
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assert_eq!(vec![1, 1], foo.next().unwrap());
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assert_eq!(vec![2, 1], foo.next().unwrap());
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assert_eq!(vec![1, 2, 1, 1], foo.next().unwrap());
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assert_eq!(vec![1, 1, 1, 2, 2, 1], foo.next().unwrap());
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assert_eq!(vec![3, 1, 2, 2, 1, 1], foo.next().unwrap());
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}
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pub fn solve(input: &str) -> usize {
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let seq = input
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.chars()
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.map(|c| c.to_digit(10).unwrap() as usize)
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.collect::<Vec<usize>>();
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let mut look_and_say = LookAndSay { seq: seq };
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for _ in 0..50 {
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look_and_say.next();
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}
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look_and_say.seq.len()
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}
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struct LookAndSay {
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seq: Vec<usize>,
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}
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impl Iterator for LookAndSay {
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type Item = Vec<usize>;
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fn next(&mut self) -> Option<Vec<usize>> {
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let mut s = Vec::new();
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let mut digit = self.seq[0];
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let mut count = 0;
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for &i in &self.seq {
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if i != digit {
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s.push(count);
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s.push(digit);
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digit = i;
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count = 1;
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} else {
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count += 1;
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}
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}
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s.push(count);
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s.push(digit);
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self.seq = s.clone();
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Some(s)
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}
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}
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