1 files changed, 71 insertions, 0 deletions
diff --git a/2016/src/bin/day05.rs b/2016/src/bin/day05.rs
new file mode 100644
index 0000000..eefa3df
--- /dev/null
+++ b/2016/src/bin/day05.rs
@@ -0,0 +1,71 @@
+extern crate crypto;
+
+use std::io::{self, Read};
+
+use crypto::digest::Digest;
+use crypto::md5::Md5;
+
+fn solve1(input: &str) -> String {
+    let mut password = String::new();
+    let mut index = 0u64;
+
+    while password.len() < 8 {
+        let mut md5 = Md5::new();
+        md5.input_str(input);
+        md5.input_str(&index.to_string());
+        let digest = md5.result_str();
+
+        if &digest[0..5] == "00000" {
+            password.push_str(&digest[5..6]);
+        }
+
+        index += 1;
+    }
+
+    password
+}
+
+fn solve2(input: &str) -> String {
+    let mut password = [None; 8];
+    let mut index = 0u64;
+
+    while !password.iter().all(Option::is_some) {
+        let mut md5 = Md5::new();
+        md5.input_str(input);
+        md5.input_str(&index.to_string());
+        let digest = md5.result_str();
+
+        if &digest[0..5] == "00000" {
+            if let Some(pos @ 0 ... 7) = digest[5..6].parse().ok() {
+                password[pos] = password[pos].or(digest[6..7].chars().next());
+            }
+        }
+
+        index += 1;
+    }
+
+    password.iter()
+        .cloned()
+        .map(Option::unwrap)
+        .collect()
+}
+
+fn main() {
+    let mut input = String::new();
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    println!("Part 1: {}", solve1(input.trim()));
+    println!("Part 2: {}", solve2(input.trim()));
+}
+
+#[test]
+#[ignore]
+fn part1() {
+    assert_eq!("18f47a30", solve1("abc"));
+}
+
+#[test]
+#[ignore]
+fn part2() {
+    assert_eq!("05ace8e3", solve2("abc"));
+}