50 lines
1.9 KiB
Rust
50 lines
1.9 KiB
Rust
use std::io::{self, BufRead};
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fn split_into_numbers(x: &str) -> impl Iterator<Item = i32> + '_ {
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return x.split(' ').filter(|&n| {n != "" && n != " "}).map(|n| n.parse::<i32>().unwrap());
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}
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fn main() {
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let input = "input.txt";
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let lines = read_lines(&input);
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let n_cards: usize = read_lines(&input).count();
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let mut cards: Vec<u32> = vec![1; n_cards];
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let mut sum_points: u32 = 0;
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// number of copies per card
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for (i, line) in lines.enumerate() {
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let mut points: u32 = 0;
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let mut n_matches: usize = 0;
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let Ok(card) = line else { panic!("Line not ok"); };
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let Some(colon) = card.find(':') else { panic!("Could not find ':'"); };
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let Some(pipe) = card.find('|') else { panic!("Could not find '|'"); };
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// let split_into_numbers = |x: &str| { return x.split(' ').filter(|&n| {n != "" && n != " "}).map(|n| n.parse::<i32>().unwrap()); };
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let winning_numbers: Vec<i32> = split_into_numbers(&card[colon+2..pipe-1]).collect();
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for number in split_into_numbers(&card[pipe+2..]) {
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if winning_numbers.contains(&number) {
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// task 1
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if points == 0 { points = 1; }
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else { points <<= 1; }
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// task 2
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if points == 0 { points = 1; }
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n_matches += 1;
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}
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}
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// task 1
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sum_points += points;
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// task 2: add #copies(card i) to the next n_matches cards
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for j in i+1..i+1+n_matches {
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cards[j] += cards[i];
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}
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}
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println!("Total points: {}", sum_points);
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println!("Total number of cards: {}", cards.iter().sum::<u32>());
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}
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fn read_lines<P>(filename: P) -> io::Lines<io::BufReader<std::fs::File>>
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where P: AsRef<std::path::Path>, {
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return match std::fs::File::open(filename) {
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Err(why) => panic!("Could not open file. {}", why),
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Ok(file) => std::io::BufReader::new(file).lines()
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};
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}
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