Advent of Code 2024 - Day 1

use std::fs::File;
use std::io::prelude::*;

fn split_input(inputs: &String, first_list: &mut Vec<i32>, second_list: &mut Vec<i32>) {
    for (_index, line) in inputs.lines().enumerate() {
        let parts: Vec<&str> = line.split_whitespace().collect();

        first_list.push(parts[0].parse().unwrap());
        second_list.push(parts[1].parse().unwrap());

    }
}

fn get_smallest_num(first_list: &mut Vec<i32>, second_list: &mut Vec<i32>) -> [i32; 2] {
    let min_first = *first_list.iter().min().unwrap();
    let min_second = *second_list.iter().min().unwrap();

    first_list.sort();
    second_list.sort();

    if let Ok(index) = first_list.binary_search(&min_first) {
        first_list.remove(index);
    }

    if let Ok(index) = second_list.binary_search(&min_second) {
        second_list.remove(index);
    }

    [min_first, min_second]
}

fn get_num_appears(num: &i32, second_list: &Vec<i32>) -> usize {
    let indices: Vec<usize>;

    indices = second_list.iter().enumerate().filter_map(|(i, &x)| if x == *num {Some(i) } else { None }).collect();
    indices.len()
}

fn main() -> std::io::Result<()> {
    let mut file = File::open("input.txt")?;
    let mut inputs = String::new();
    let mut first_list: Vec<i32> = Vec::new();
    let mut second_list: Vec<i32> = Vec::new();
    let mut smallest_num: [i32; 2];
    let mut result: i32 = 0;

    file.read_to_string(&mut inputs)?;

    // PART ONE 
    split_input(&inputs, &mut first_list, &mut second_list);

    while first_list.len() != 0 {
        smallest_num = get_smallest_num(&mut first_list, &mut second_list);
        result += (smallest_num[0] - smallest_num[1]).abs();
    }

    println!("Part One : {}", result);

    // PART TWO
    result = 0;
    split_input(&inputs, &mut first_list, &mut second_list);

    for num in first_list {
        let appear = get_num_appears(&num, &second_list);
        result += num * appear as i32;
    }

    println!("Part Two : {}", result);

    Ok(())
}