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path: root/2016/src/bin/day03.rs
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use std::io::{self, Read};
use std::str::FromStr;

struct Triangle(u32, u32, u32);

impl Triangle {
    fn valid(&self) -> bool {
        self.0 + self.1 > self.2
            && self.1 + self.2 > self.0
            && self.0 + self.2 > self.1
    }
}

impl FromStr for Triangle {
    type Err = ();
    fn from_str(s: &str) -> Result<Self, ()> {
        let mut iter = s.split_whitespace().map(str::parse);
        match (iter.next(), iter.next(), iter.next()) {
            (Some(Ok(a)), Some(Ok(b)), Some(Ok(c))) => Ok(Triangle(a, b, c)),
            _ => Err(()),
        }
    }
}

fn solve1(input: &str) -> usize {
    input.lines()
        .map(str::parse)
        .map(Result::unwrap)
        .filter(Triangle::valid)
        .count()
}

fn solve2(input: &str) -> usize {
    let triangles: Vec<Triangle> = input.lines()
        .map(str::parse)
        .map(Result::unwrap)
        .collect();

    triangles.chunks(3)
        .flat_map(|triple| {
            vec![
                Triangle(triple[0].0, triple[1].0, triple[2].0),
                Triangle(triple[0].1, triple[1].1, triple[2].1),
                Triangle(triple[0].2, triple[1].2, triple[2].2),
            ]
        })
        .filter(Triangle::valid)
        .count()
}

fn main() {
    let mut input = String::new();
    io::stdin().read_to_string(&mut input).unwrap();

    println!("Part 1: {}", solve1(&input));
    println!("Part 2: {}", solve2(&input));
}

#[test]
fn part1() {
    assert_eq!(0, solve1("5 10 25"));
}
e266237355&follow=1'>ui-summary: Use default branch for readme if : prefixJason A. Donenfeld 2013-05-25cgit.c: Do not reset HOME after unsetting it.Jason A. Donenfeld 2013-05-25cgit.c: sync repo config printing with struct cgit_repoJason A. Donenfeld 2013-05-25git: update to 1.8.3John Keeping 2013-05-22cache.c: cache ls_cache output properlyJohn Keeping 2013-05-22tests: introduce strip_header() helper functionJohn Keeping 2013-05-22shared.c: use die_errno() where appropriateJohn Keeping 2013-05-22html.c: die when write failsJohn Keeping 2013-05-22ui-log: add <span/> around commit decorationsJohn Keeping 2013-05-22Makefile: fix parallel "make test"John Keeping 2013-05-18cache.c: fix cache_lsJohn Keeping 2013-05-13t0109: "function" is a bash-ismJohn Keeping 2013-05-13New mailing list.Jason A. Donenfeld 2013-04-30ui-snapshot: do not access $HOMEJason A. Donenfeld 2013-04-27t0001: validate Git -rcN version numbers correctlyJohn Keeping 2013-04-27git: update to 1.8.2.2John Keeping 2013-04-17scan-tree: fix regression in section-from-path=-1John Keeping 2013-04-15t0001: ignore ".dirty" suffix on Git versionJohn Keeping 2013-04-15tests: set TEST_OUTPUT_DIRECTORY to the CGit test directoryJohn Keeping 2013-04-15t0109: test more URLsJohn Keeping 2013-04-10cgitrc.5.txt: Specify when scan-path must be defined before.Jason A. Donenfeld 2013-04-10ui-snapshot.c: Prepend "V" when guessing ref namesLukas Fleischer 2013-04-10t0107: Skip ZIP tests if unzip(1) isn't availableLukas Fleischer 2013-04-10tests/: Do not use `sed -i`Lukas Fleischer 2013-04-10Add branch-sort and repo.branch-sort options.Jason A. Donenfeld 2013-04-10t0109: chain operations with &&John Keeping 2013-04-10cgit.c: Do not restore unset environment variablesLukas Fleischer 2013-04-09t0107: Use `tar -z` for gzip'ed archivesLukas Fleischer