2 files changed, 93 insertions, 0 deletions
diff --git a/d05/Cargo.toml b/d05/Cargo.toml
new file mode 100644
index 0000000..38415e6
--- /dev/null
+++ b/d05/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "d05"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+md5 = "0.7.0"
diff --git a/d05/src/main.rs b/d05/src/main.rs
new file mode 100644
index 0000000..25986ef
--- /dev/null
+++ b/d05/src/main.rs
@@ -0,0 +1,86 @@
+use md5;
+
+fn solve_part1(seed: &str) -> String {
+    let mut passw = String::new();
+
+    let mut i = 0;
+    loop {
+        let data = format!("{}{}", seed, i.to_string());
+        let hash = format!("{:x}", md5::compute(data));
+
+        // We've mined a block, so-- wait wrong software
+        if hash.starts_with("00000") {
+            passw.push(hash.chars().nth(5).unwrap());
+            if passw.len() >= 8 {
+                break;
+            }
+        }
+
+        i += 1;
+    }
+
+    passw
+}
+
+fn solve_part2(seed: &str) -> String {
+    // We'll replace each `x' with the true character
+    let mut passw = String::from("xxxxxxxx");
+
+    let mut i = 0;
+    loop {
+        let data = format!("{}{}", seed, i.to_string());
+        let hash = format!("{:x}", md5::compute(data));
+
+        // I wonder how this loop affects global power consumption...
+        if hash.starts_with("00000") {
+            let c = hash.chars().nth(5).unwrap();
+            if c.is_ascii_digit() {
+                // Get index of character to replace
+                let k = String::from(c).parse().unwrap();
+
+                // Is `k' in bounds, and haven't we replaced `passw[k]' already?
+                if k < 8 && passw.chars().nth(k).unwrap() == 'x' {
+                    let s = String::from(hash.chars().nth(6).unwrap());
+                    passw.replace_range(k..k + 1, &s);
+
+                    // Have we replaced all characters in `passw'?
+                    if !passw.contains('x') {
+                        break;
+                    }
+                }
+            }
+        }
+
+        i += 1;
+    }
+
+    passw
+}
+
+fn main() {
+    // My personal input ID
+    let id = "ugkcyxxp";
+
+    // Part 1 gives "d4cd2ee1" for me
+    println!("Part 1 solution: {}", solve_part1(id));
+
+    // Part 2 gives "f2c730e5" for me
+    println!("Part 2 solution: {}", solve_part2(id));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_example1() {
+        let id = "abc";
+        assert_eq!(solve_part1(id), "18f47a30");
+    }
+
+    #[test]
+    fn part2_example1() {
+        let id = "abc";
+        assert_eq!(solve_part2(id), "05ace8e3");
+    }
+}