#[test]
fn split_line() {
    let lines = vec![100, 200, 300];
    let input = String::from("100   200   300");
    assert_eq!(lines, split(input))
}

#[test]
fn test_min_max() {
    let input = String::from("100   200   300");
    let split = split(input);
    assert_eq!((100, 300), get_min_max(split))
}

#[test]
fn test_diff() {
    let input = String::from("100   200   300");
    let split = split(input);
    let (min, max) = get_min_max(split);
    assert_eq!(200, diff(min, max))
}

#[test]
fn test_main() {
    let input = "5 1 9 5
7 5 3
2 4 6 8";
    let result = checksum(input);
    assert_eq!(18, result);
}

fn split(s : String) -> Vec<i32> {
    s.split_whitespace().map(|x| x.parse::<i32>().unwrap()).collect()
}

fn get_min_max(nums : Vec<i32>) -> (i32, i32) {
    let min = *nums.iter().min().unwrap();
    let max = *nums.iter().max().unwrap();
    (min, max)
}

fn diff(min : i32, max : i32) -> i32 {
    max - min
}

fn checksum(input_str : &str) -> i32 {
    let mut out : i32 = 0;
    for line in input_str.lines() {
        let split = split(String::from(line));
        let (min, max) = get_min_max(split);
        let diff = diff(min, max);
        out += diff;
    }
    out
}