pastemyst | aoc day 5

aoc day 5

main.rs

Rustcopy raw

use std::collections::LinkedList;
use std::io;
use std::io::Read;

fn main() {
    // get input as lines
    let mut buf: String = String::new();
    io::stdin().read_to_string(&mut buf).unwrap();
    let mut lines: Vec<&str> = buf.split('\n').collect();
    lines.pop(); // newline at end of file

// get separator between initial setup <=> operations
    let mut ind: usize = 0;
    while lines[ind].len() > 0 { ind += 1; }

// init stacks
    let mut stacks: Vec<LinkedList<char>> = vec![];
    let ns = (lines[ind-1].len() + 1) / 4;
    for _ in 0..ns { stacks.push(LinkedList::new()); }

// make initial state
    for i in (0..ind - 1).rev() {
        println!("{}", lines[i]);
        let l: Vec<char> = lines[i].chars().collect();
        for j in 0..ns {
            if l[j*4 + 1] != ' ' {
                stacks[j].push_back(l[j*4 + 1]);
            }
        }
    }

// move stacks
    for i in ind + 1..lines.len() {
        let l: Vec<&str> = lines[i].split_ascii_whitespace().collect();
        let (a, b, c): (usize, usize, usize) = ( // get the number parts. terrible code. whatever
            l[1].parse::<>().unwrap(),
            l[3].parse::<>().unwrap(),
            l[5].parse::<>().unwrap()
        );

move_crates_p2(&mut stacks, a, b-1, c-1); // switch to move_crates_p1 for part 1
    }

// output
    for s in stacks {
        print!("{}", s.back().unwrap());
    }
    println!(); // not strictly necessary but my shell yells at me if i don't always output a newline at the end
}

fn move_crates_p2(crates: &mut Vec<LinkedList<char>>, num: usize, src: usize, dest: usize) { // part 2
    let mut queue: LinkedList<char> = LinkedList::new(); // 2 stacks = queue
    for _ in 0..num {
        let ch = crates[src].pop_back().unwrap();
        queue.push_back(ch);
    }
    while !queue.is_empty() {
        crates[dest].push_back(queue.pop_back().unwrap());
    }
}

fn move_crates_p1(crates: &mut Vec<LinkedList<char>>, num: usize, src: usize, dest: usize) { // part 1
    for _ in 0..num {
        let ch = crates[src].pop_back().unwrap();
        crates[dest].push_back(ch);
    }
}

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