AdventOfCode/day5/src/main.rs

use std::fs;
use std::char;

fn main() {
    let lines = fs::read_to_string("input").expect("Unable to read file");

    //Part 1
    println!("{}", reduce(lines.clone()));

    //Part 2

    let mut all_lengths: Vec<i32> = Vec::new();

    for i in 0..26 {
        let big_char = char::from_u32(65+i).unwrap();
        let little_char = char::from_u32(97+i).unwrap();

        let string = lines.clone().replace(big_char, "").replace(little_char, "");

        all_lengths.push(reduce(string));
    }

    println!("{}", all_lengths.iter().min().unwrap());
}

fn reduce(string: String) -> i32 {
    let all_chars: Vec<char> = string.chars().into_iter().collect();

    let mut stack: Vec<char> = Vec::new();

    for c in all_chars{
        if !stack.is_empty(){
            let sub = *stack.last().unwrap() as i32 - c as i32;
            if sub == 32 || sub == -32 {
                stack.pop();
            } else{
                stack.push(c.clone());
            }
        } else {
            stack.push(c.clone());
        }
    }

    return stack.len() as i32
}