86 lines
1.6 KiB
Rust
86 lines
1.6 KiB
Rust
#![feature(test)]
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extern crate test;
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use aoc2020::common::*;
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use itertools::{Itertools, MinMaxResult};
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fn read_input() -> String {
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read_file(9)
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}
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fn parse_input(raw: &str) -> Vec<usize> {
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raw.lines().map(|l| l.parse().unwrap()).collect()
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}
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fn part1(input: &[usize], window_size: usize) -> usize {
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*input
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.windows(window_size + 1)
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.find_map(|xs| {
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xs.last()
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.filter(|last| !xs[..window_size].iter().tuple_combinations().any(|(a, b)| a + b == **last))
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})
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.unwrap()
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}
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fn part2(input: &[usize], bad_num: usize) -> usize {
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(0..input.len()).find_map(|i| sum_up_to(&input[i..], bad_num)).unwrap()
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}
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fn sum_up_to(input: &[usize], n: usize) -> Option<usize> {
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let mut acc = input[0];
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for x in 1..input.len() {
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acc += input[x];
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if acc == n {
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return match input[..x].iter().minmax() {
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MinMaxResult::MinMax(min, max) => Some(min + max),
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_ => unreachable!(),
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};
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}
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if acc > n {
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return None;
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}
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}
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None
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}
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fn main() {
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let input = parse_input(&read_input());
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let p1 = part1(&input, 25);
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println!("Part 1: {}", p1);
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println!("Part 2: {}", part2(&input, p1));
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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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use test::black_box;
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use aoc2020::*;
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use paste::paste;
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const TEST_INPUT: &str = "35
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20
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15
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25
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47
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40
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62
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55
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65
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95
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102
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117
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150
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182
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127
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219
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299
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277
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309
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576";
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test!(part1(5) == 127);
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test!(part2(127) == 62);
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bench!(part1(25) == 393911906);
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bench!(part2(393911906) == 59341885);
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}
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