100 lines
2.3 KiB
Rust
100 lines
2.3 KiB
Rust
use std::fs::read_to_string;
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use itertools::Itertools;
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use regex::Regex;
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pub fn day_main() {
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let input = read_to_string("input/day13.txt").unwrap();
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let input = input.trim();
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println!(" part1: {}", part1(input));
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println!(" part2: {}", part2(input));
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}
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type RiddleResult = i64;
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fn part1(input: &str) -> RiddleResult {
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// Button A: X+30, Y+84
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// Button B: X+74, Y+60
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// Prize: X=2358, Y=2628
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let r = Regex::new(
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r"Button A: X\+(\d+), Y\+(\d+)
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Button B: X\+(\d+), Y\+(\d+)
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Prize: X=(\d+), Y=(\d+)",
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)
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.unwrap();
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r.captures_iter(input)
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.map(|block| {
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let (ax, ay, bx, by, px, py) = block
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.iter()
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.skip(1)
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.map(|it| it.unwrap().as_str().parse::<i64>().unwrap())
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.collect_tuple()
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.unwrap();
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solve((ax, ay, bx, by, px, py)).unwrap_or(0)
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})
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.sum()
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}
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fn part2(input: &str) -> RiddleResult {
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let r = Regex::new(
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r"Button A: X\+(\d+), Y\+(\d+)
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Button B: X\+(\d+), Y\+(\d+)
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Prize: X=(\d+), Y=(\d+)",
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)
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.unwrap();
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r.captures_iter(input)
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.map(|block| {
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let (ax, ay, bx, by, px, py) = block
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.iter()
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.skip(1)
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.map(|it| it.unwrap().as_str().parse::<i64>().unwrap())
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.collect_tuple()
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.unwrap();
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let solution = solve((ax, ay, bx, by, px + 10000000000000, py + 10000000000000));
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solution.unwrap_or(0)
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})
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.sum()
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}
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fn solve((ax, ay, bx, by, px, py): (i64, i64, i64, i64, i64, i64)) -> Option<RiddleResult> {
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let b = (ay * px - ax * py) / (ay * bx - ax * by);
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let a = (px - b * bx) / ax;
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if a >= 0 && b >= 0 && a * ax + b * bx == px && a * ay + b * by == py {
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Some(3 * a + b)
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} else {
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None
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}
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}
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#[cfg(test)]
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mod test {
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use super::{part1, part2};
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const TEST_INPUT: &str = r"Button A: X+94, Y+34
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Button B: X+22, Y+67
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Prize: X=8400, Y=5400
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Button A: X+26, Y+66
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Button B: X+67, Y+21
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Prize: X=12748, Y=12176
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Button A: X+17, Y+86
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Button B: X+84, Y+37
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Prize: X=7870, Y=6450
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Button A: X+69, Y+23
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Button B: X+27, Y+71
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Prize: X=18641, Y=10279
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";
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#[test]
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fn test1() {
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assert_eq!(part1(TEST_INPUT), 480);
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}
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#[test]
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fn test2() {
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assert_eq!(part2(TEST_INPUT), 875318608908);
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}
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}
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