Day 05: Doesn’t He Have Intern-Elves For This?

Fairly simple map, filter, reduce problem. Read in the lines, apply rules, count the end size. The rules could have been implemented better by me but they are all small enough in scope I don’t mind.

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day_05.rs

use std::char;

fn parse_input (input: &str) -> impl Iterator<Item = Vec<char>> + '_ {
	return input.lines().map(|x| x.chars().collect::<Vec<_>>())
}

fn count_vowels (line: &Vec<char>) -> usize {
	let vowels = ['a', 'e', 'i', 'o', 'u'];
	
	return line.iter()
		.map(|x| if vowels.contains(x) { 1 } else { 0 })
		.sum();
}

fn contains_letter_pair (line: &Vec<char>) -> bool {
	for i in 1..line.len() {
		if line[i - 1] == line[i] { return true; }
	}
	return false;
}

fn contains_bad_string (line: &Vec<char>) -> bool {
	let bad_strings = ["ab", "cd", "pq", "xy"];
	let line = line.iter().collect::<String>();
	return bad_strings.iter().any(|x| line.contains(x));
}

pub fn day_05_1 (input: &str) -> String {
	return parse_input(input)
		.filter(|x| contains_bad_string(x) == false)
		.filter(|x| contains_letter_pair(x) == true)
		.filter(|x| 3 <= count_vowels(x))
		.count()
		.to_string();
}

fn has_double_no_overlap (line: &Vec<char>) -> bool {
	for i in 0..line.len() - 3 {
		for j in (i+2)..line.len() - 1 {
			if line[i] == line[j] && line[i + 1] == line[j + 1] {
				return true;
			}
		}
	}
	return false;
}

fn has_repeat_with_gap (line: &Vec<char>) -> bool {
	for i in 2..line.len() {
		if line[i] == line[i - 2] {
			return true;
		}
	}
	return false;
}

pub fn day_05_2 (input: &str) -> String {
	return parse_input(input)
		.filter(|x| has_repeat_with_gap(x) == true)
		.filter(|x| has_double_no_overlap(x) == true)
		.count()
		.to_string();
}