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use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
use std::collections::BTreeMap;
#[derive(Debug)]
struct Room {
encrypted_name: String,
sector_id: u32,
checksum: String
}
impl Room {
fn new(line: String) -> Room {
let name_length = line.find(char::is_numeric).unwrap();
let (name, sector_and_check) = line.split_at(name_length);
let (sector, check) = sector_and_check.split_at(sector_and_check.len()-7);
Room {
encrypted_name: name.trim_matches('-').to_string(),
sector_id: sector.parse().unwrap(),
checksum: check.trim_matches(|c| c=='[' || c==']').to_string()
}
}
fn is_valid(&self) -> bool {
let mut char_counts: BTreeMap<char, i32> = BTreeMap::new();
let chars = self.encrypted_name.chars()
.filter(|&c| c != '-');
for c in chars {
*char_counts.entry(c).or_insert(0) += 1;
}
let mut vec_char_counts = char_counts.iter().collect::<Vec<_>>();
vec_char_counts.sort_by_key(|&(_, &value)| -value);
let expected_checksum = vec_char_counts
.iter()
.take(5)
.map(|&(&key, _)| key)
.collect::<String>();
expected_checksum == self.checksum
}
fn decrypt_name(&self) -> String {
self.encrypted_name.chars().map(|c| {
if c == '-' {
' '
} else {
let current_digit = c as u8 - 'a' as u8;
let new_digit = ((current_digit as u32 + self.sector_id) % 26) as u8;
(new_digit + 'a' as u8) as char
}
}).collect()
}
}
fn main() {
let rooms = read_file();
let valid_rooms = rooms.iter()
.filter(|r| r.is_valid())
.collect::<Vec<_>>();
let sector_sum: u32 = valid_rooms.iter()
.map(|r| r.sector_id)
.sum();
println!("Sector sum {}", sector_sum);
let north_poles = rooms.iter()
.filter(|r| r.decrypt_name().contains("north"))
.inspect(|r| println!("{} {}", r.decrypt_name(), r.sector_id))
.collect::<Vec<_>>();
println!("{:?}", north_poles);
}
fn read_file() -> Vec<Room> {
let file = BufReader::new(File::open("input.txt").unwrap());
file.lines()
.map(|line| line.unwrap().trim().to_string())
.filter(|line| line.len() > 0)
.map(Room::new)
.collect()
}
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