You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
advent-of-code/2016/rust/src/day_05.rs

65 lines
1.4 KiB

use std::char;
use crypto::digest::Digest;
use crypto::md5::Md5;
use errors::*;
pub fn solve(input: &str) -> Result<String> {
let pw = Password::new(input.trim());
Ok(pw.take(8).collect())
}
struct Password {
id: String,
index: usize,
md5: Md5,
}
impl Password {
fn new(id: &str) -> Self {
Password{id: id.into(), index: 0, md5: Md5::new()}
}
}
impl Iterator for Password {
// we will be counting with usize
type Item = char;
// next() is the only required method
fn next(&mut self) -> Option<char> {
let mut result = None;
let mut hash = [0; 16];
while result.is_none() {
let input = format!("{}{}", self.id, self.index);
self.index += 1;
self.md5.input_str(&input);
self.md5.result(&mut hash);
self.md5.reset();
if self.index % 1000000 == 0 {
println!("{}", self.index);
}
if hash[0] as u16 + hash[1] as u16 + (hash[2] >> 4) as u16 == 0 {
result = Some(char::from_digit((hash[2] & 0b00001111) as u32, 16).unwrap());
break
}
}
result
}
}
#[test]
fn test_password() {
let mut pw = Password{id: "abc".into(), index: 3231928, md5: Md5::new()};
assert_eq!(pw.next(), Some('1'.into()));
assert_eq!(pw.index, 3231930);
let mut pw = Password{id: "abc".into(), index: 5017308, md5: Md5::new()};
assert_eq!(pw.next(), Some('8'.into()));
assert_eq!(pw.next(), Some('f'.into()));
}