diff --git a/2016/rust/src/day_04.rs b/2016/rust/src/day_04.rs
index 121f9b6..1286307 100644
--- a/2016/rust/src/day_04.rs
+++ b/2016/rust/src/day_04.rs
@@ -1,3 +1,4 @@
+use std::char;
use std::cmp::Ordering;
use std::collections::HashMap;
@@ -15,12 +16,12 @@ pub fn solve(input: &str) -> Result<String> {
Room::new(room).map(|room| (room, checksum.into()))
})
.collect::<Result<_>>()?;
- let real_rooms = rooms.iter()
- .filter(|&&(ref room, ref checksum)| room.checksum() == *checksum);
- let sector_ids = real_rooms.map(|&(ref room, _)| room.sector_id);
- let sum: usize = sector_ids.sum();
+ let mut real_rooms = rooms.iter()
+ .filter(|&&(ref room, ref checksum)| room.checksum() == *checksum)
+ .map(|&(ref room, _)| room);
+ let room = real_rooms.find(|room| room.name().contains("north")).ok_or("")?;
- Ok(sum.to_string())
+ Ok(room.sector_id.to_string())
}
#[test]
@@ -59,6 +60,19 @@ impl Room {
counts.iter().take(5).map(|x| *x.0).collect()
}
+
+ fn name(&self) -> String {
+ self.encrypted_name.chars().map(|c| {
+ match c {
+ '-' => ' ',
+ c => {
+ let digit = c.to_digit(36).unwrap() - 10;
+ let shifted = (digit + self.sector_id as u32) % 26;
+ char::from_digit(shifted + 10, 36).unwrap()
+ },
+ }
+ }).collect()
+ }
}
#[test]
@@ -82,3 +96,9 @@ fn test_checksum() {
let room = Room::new("totally-real-room-200").unwrap();
assert_ne!(room.checksum(), "decoy".to_string());
}
+
+#[test]
+fn test_name() {
+ let room = Room::new("qzmt-zixmtkozy-ivhz-343").unwrap();
+ assert_eq!(room.name(), "very encrypted name");
+}