use std::{collections::HashMap, iter::zip};

pub fn process_part1(input: &str) -> i32 {
    let mut left = Vec::new();
    let mut right = Vec::new();
    input.lines().for_each(|line| {
        let (left_val, right_val) = line.split_once("   ").unwrap();
        left.push(left_val.parse::<i32>().unwrap());
        right.push(right_val.parse::<i32>().unwrap());
    });
    left.sort();
    right.sort();
    let mut res = 0;
    for (left_val, right_val) in zip(left, right) {
        res += (left_val - right_val).abs();
    }
    res
}

pub fn process_part2(input: &str) -> i32 {
    let mut left = Vec::new();
    let mut right = HashMap::new();
    input.lines().for_each(|line| {
        let (left_val, right_val) = line.split_once("   ").unwrap();
        left.push(left_val.parse::<i32>().unwrap());
        right
            .entry(right_val.parse::<i32>().unwrap())
            .and_modify(|value| *value += 1)
            .or_insert(1);
    });
    left.sort();
    let mut res = 0;
    for left_val in left {
        let right_val_count = right.get(&left_val).unwrap_or(&0);
        res += left_val * right_val_count;
    }
    res
}

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

    const INPUT: &str = "3   4
4   3
2   5
1   3
3   9
3   3";

    #[test]
    fn part1() {
        let result = process_part1(INPUT);
        assert_eq!(result, 11);
    }

    #[test]
    fn part2() {
        let result = process_part2(INPUT);
        assert_eq!(result, 31);
    }
}