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#![allow(dead_code)]
use std::fs;
use std::collections::HashSet;
use regex::Regex;
fn read_file(file: &str) -> String {
fs::read_to_string(file).unwrap()
}
fn read_lines(file: &str) -> Vec<String> {
read_file(file).split('\n')
.filter(|x| !x.is_empty())
.map(String::from)
.collect()
}
fn read_numbers(file: &str) -> Vec<i32> {
read_file(file).split('\n')
.filter(|x| !x.is_empty())
.map(|x| x.parse::<i32>().unwrap())
.collect()
}
fn find_pair_with_sum(numbers: &HashSet<i32>, goal: i32) -> Option<(i32, i32)> {
for i in numbers {
if numbers.contains(&(goal - i)) {
return Some((*i, goal - i));
}
}
None
}
fn day1() {
let input = read_numbers("input01");
let mut numbers = HashSet::new();
for i in &input {
numbers.insert(*i);
}
let (x, y) = match find_pair_with_sum(&numbers, 2020) {
Some(pair) => pair,
None => panic!("nothing found"),
};
println!("1a: {}", x * y);
for i in &numbers {
let (x, y) = match find_pair_with_sum(&numbers, 2020 - i) {
Some(pair) => pair,
None => continue,
};
println!("1b: {}", i * x * y);
break;
}
}
struct PasswordEntry {
min : usize,
max : usize,
character : char,
password : String,
}
impl PasswordEntry {
fn new(input: &str) -> PasswordEntry {
let re = Regex::new(r"^([0-9]+)-([0-9]+) ([a-z]): ([a-z]+)$").unwrap();
let caps = re.captures(&input).unwrap();
PasswordEntry {
min : caps[1].parse::<usize>().unwrap(),
max : caps[2].parse::<usize>().unwrap(),
character : caps[3].parse::<char>().unwrap(),
password : caps[4].to_string(),
}
}
fn is_valid(&self) -> bool {
let count = self.password.chars().filter(|x| *x == self.character).count();
count >= self.min && count <= self.max
}
fn is_valid_new(&self) -> bool {
let c1 = self.password.chars().nth(self.min-1).unwrap();
let c2 = self.password.chars().nth(self.max-1).unwrap();
c1 != c2 && (c1 == self.character || c2 == self.character)
}
}
fn day2() {
let input : Vec<PasswordEntry> = read_lines("input02")
.iter()
.map(|x| PasswordEntry::new(&x))
.collect();
let count = input.iter()
.filter(|x| x.is_valid())
.count();
println!("2a: {}", count);
let count = input.iter()
.filter(|x| x.is_valid_new())
.count();
println!("2b: {}", count);
}
fn main() {
day2();
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_day1() {
let input = [1721, 979, 366, 299, 675, 1456];
let mut numbers = HashSet::new();
for i in &input {
numbers.insert(*i);
}
let (x, y) = find_pair_with_sum(&numbers, 2020).unwrap();
assert_eq!(x * y, 514579);
for i in &numbers {
let (x, y) = match find_pair_with_sum(&numbers, 2020 - i) {
Some(pair) => pair,
None => continue,
};
assert_eq!(i + x + y, 2020);
assert_eq!(i * x * y, 241861950);
break;
}
}
#[test]
fn test_day2() {
let lines = ["1-3 a: abcde",
"1-3 b: cdefg",
"2-9 c: ccccccccc"];
let entries : Vec<PasswordEntry> = lines.iter().map(|x| PasswordEntry::new(&x)).collect();
assert_eq!(entries[0].is_valid(), true);
assert_eq!(entries[1].is_valid(), false);
assert_eq!(entries[2].is_valid(), true);
assert_eq!(entries[0].is_valid_new(), true);
assert_eq!(entries[1].is_valid_new(), false);
assert_eq!(entries[2].is_valid_new(), false);
}
}
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