Rust

use num::{BigInt, Integer};

pub fn solve_part_1(input: &str) -> String {
    let gears: Vec<i64> = input.trim().lines().map(|g| g.parse().unwrap()).collect();
    (2025 * gears[0] / gears.last().unwrap()).to_string()
}

pub fn solve_part_2(input: &str) -> String {
    let gears: Vec<i64> = input.trim().lines().map(|g| g.parse().unwrap()).collect();
    let res = (BigInt::parse_bytes(b"10000000000000", 10).unwrap() * gears.last().unwrap())
        .div_ceil(&(BigInt::ZERO + gears[0]));
    res.to_string()
}

pub fn solve_part_3(input: &str) -> String {
    let mut lines = input.trim().lines();
    let first_gear = BigInt::parse_bytes(lines.next().unwrap().as_bytes(), 10).unwrap();
    let mut nominator: BigInt = first_gear * 100;
    let mut denominator: BigInt = BigInt::ZERO + 1;
    for line in lines {
        let mut split = line.split("|");
        denominator *= BigInt::parse_bytes(split.next().unwrap().as_bytes(), 10).unwrap();
        match split.next() {
            Some(size) => {
                nominator *= BigInt::parse_bytes(size.as_bytes(), 10).unwrap();
            }
            None => {
                break;
            }
        }
    }
    (nominator / denominator).to_string()
}