45 lines
889 B
Rust
45 lines
889 B
Rust
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mod common;
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fn main() {
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let input = common::day_input(2);
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let bytes = input.as_bytes();
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println!("Part 1: {}", part1(bytes));
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println!("Part 2: {}", part2(bytes));
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}
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fn sum_outcomes(b: &[u8], t: [isize; 3]) -> i32 {
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(0..b.len()).step_by(4).fold(0, |p, x| {
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let y: usize = ((b[x] - 65) % 3).into();
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p + [[4, 8, 3], [1, 5, 9], [7, 2, 6]][y as usize]
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[((((b[x + 2] - 88) % 3) as isize + t[y]).rem_euclid(3)) as usize]
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})
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}
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fn part1(input: &[u8]) -> i32 {
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sum_outcomes(input, [0, 0, 0])
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}
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fn part2(input: &[u8]) -> i32 {
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sum_outcomes(input, [-1, 0, 1])
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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const TEST_INPUT: &[u8] = "A Y
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B X
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C Z"
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.as_bytes();
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#[test]
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fn test_part1() {
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assert_eq!(part1(TEST_INPUT), 15)
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}
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#[test]
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fn test_part2() {
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assert_eq!(part2(TEST_INPUT), 12)
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}
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}
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