68 lines
1.7 KiB
Rust
68 lines
1.7 KiB
Rust
#![feature(test)]
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extern crate test;
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use aoc2023::{boilerplate, common::*};
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use itertools::Itertools;
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const DAY: usize = 9;
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type I = i64;
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type Parsed = Vec<Vec<I>>;
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fn parse_input(raw: &str) -> Parsed {
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raw.lines().map(|l| parse_nums_separator(l, ' ')).collect()
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}
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fn build_levels(levels: &mut Parsed) {
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loop {
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let previous = levels.last().unwrap();
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let level = previous.iter().zip(previous.iter().skip(1)).map(|(a, b)| b - a).collect_vec();
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levels.push(level);
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if levels.last().unwrap().iter().all(|n| n == &0) {
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break;
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}
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}
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}
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fn part1(lines: &Parsed) -> I {
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lines
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.iter()
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.map(|line| {
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let mut levels = vec![line.to_owned()];
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build_levels(&mut levels);
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for i in (1..levels.len()).rev() {
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let new = levels[i].last().unwrap_or(&0) + levels[i - 1].last().unwrap();
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levels[i - 1].push(new);
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}
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*levels[0].last().unwrap()
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})
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.sum()
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}
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fn part2(lines: &Parsed) -> I {
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lines
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.iter()
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.map(|line| {
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let mut levels = vec![line.to_owned()];
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build_levels(&mut levels);
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for i in (1..levels.len()).rev() {
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let new = levels[i - 1].first().unwrap_or(&0) - levels[i][0];
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levels[i - 1].insert(0, new);
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}
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levels[0][0]
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})
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.sum()
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}
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boilerplate! {
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TEST_INPUT == "\
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0 3 6 9 12 15
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1 3 6 10 15 21
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10 13 16 21 30 45",
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tests: {
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part1: { TEST_INPUT => 114 },
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part2: { TEST_INPUT => 2 },
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},
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bench1 == 2038472161,
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bench2 == 1091,
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bench_parse: Vec::len => 200,
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}
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