[2016][rust][5.1]

2016/rust/src/day_05.rs

@@ -1,4 +1,5 @@
 use std::char;
+use std::collections::HashMap;
 
 use crypto::digest::Digest;
 use crypto::md5::Md5;
@@ -6,8 +7,17 @@ use crypto::md5::Md5;
 use errors::*;
 
 pub fn solve(input: &str) -> Result<String> {
-  let pw = Password::new(input.trim());
-  Ok(pw.take(8).collect())
+  let mut pw = Password::new(input.trim());
+  let mut solution = HashMap::new();
+  while solution.len() < 8 {
+    let candidate = pw.next().unwrap();
+    if candidate.0 < 8 {
+      solution.entry(candidate.0).or_insert(candidate.1);
+    }
+  }
+  let mut v = solution.iter().collect::<Vec<_>>();
+  v.sort();
+  Ok(v.iter().map(|x| *x.1).collect::<String>())
 }
 
 struct Password {
@@ -23,11 +33,9 @@ impl Password {
 }
 
 impl Iterator for Password {
-  // we will be counting with usize
-  type Item = char;
+  type Item = (usize, char);
 
-  // next() is the only required method
-  fn next(&mut self) -> Option<char> {
+  fn next(&mut self) -> Option<(usize, char)> {
     let mut result = None;
     let mut hash = [0; 16];
 
@@ -39,12 +47,10 @@ impl Iterator for Password {
       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());
+        let pos = (hash[2] & 0b00001111) as usize;
+        let c = char::from_digit((hash[3] >> 4) as u32, 16).unwrap();
+        result = Some((pos, c));
         break
       }
     }
@@ -55,10 +61,10 @@ impl Iterator for Password {
 #[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.next(), Some((1, '5'.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()));
+  assert_eq!(pw.next(), Some((8, 'f'.into())));
+  // assert_eq!(pw.next(), Some((4, 'e'.into())));
 }