day3.rs

// vi: set shiftwidth=4 tabstop=4 expandtab:
use common::input::check_answer;
use common::input::get_answers;
use common::input::get_file_content;
use std::time::Instant;

const INPUT_FILEPATH: &str = "../resources/year2016_day3_input.txt";
const ANSWERS_FILEPATH: &str = "../resources/year2016_day3_answer.txt";

type Int = u32;
type InputContent = Vec<Vec<Int>>;

fn parse_integer_list(str: &str) -> Vec<Int> {
    str.split(' ')
        .filter(|s| !s.is_empty())
        .map(|s| s.parse::<u32>().unwrap())
        .collect()
}

fn get_input_from_str(string: &str) -> InputContent {
    string.lines().map(parse_integer_list).collect()
}

fn is_triangle(nbs: &[Int]) -> bool {
    let mut sorted = nbs.to_owned();
    sorted.sort_unstable();
    if let [a, b, c] = &*sorted {
        if a + b > *c {
            return true;
        }
    }
    false
}

fn part1(arg: &InputContent) -> usize {
    arg.iter().filter(|nbs| is_triangle(nbs)).count()
}

fn transpose(v: &InputContent) -> InputContent {
    assert!(!v.is_empty());
    let len = v[0].len();
    (0..len)
        .map(|i| v.iter().map(|row| row[i]).collect())
        .collect()
}

fn part2(arg: &InputContent) -> usize {
    transpose(arg)
        .iter()
        .map(|col| col.chunks_exact(3).filter(|nbs| is_triangle(nbs)).count())
        .sum()
}

fn main() {
    let before = Instant::now();
    let data = get_input_from_str(&get_file_content(INPUT_FILEPATH));
    let (ans, ans2) = get_answers(ANSWERS_FILEPATH);
    let solved = true;
    let res = part1(&data);
    check_answer(&res.to_string(), ans, solved);
    let res2 = part2(&data);
    check_answer(&res2.to_string(), ans2, solved);
    println!("Elapsed time: {:.2?}", before.elapsed());
}

#[cfg(test)]
mod tests {
    use super::*;

    const EXAMPLE: &str = "5 10 25
   5    10     20
2 3 4";

    const EXAMPLE2: &str = "101 301 501
102 302 502
103 303 503
201 401 601
202 402 602
203 403 603";

    #[test]
    fn test_part1() {
        assert_eq!(part1(&get_input_from_str(EXAMPLE)), 1);
    }

    #[test]
    fn test_part2() {
        assert_eq!(part2(&get_input_from_str(EXAMPLE2)), 6);
    }
}