solution: day 5 + deps

Cargo.lock

@@ -14,6 +14,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "itertools",
+ "md5",
 ]
 
 [[package]]
@@ -30,3 +31,9 @@ checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
 dependencies = [
  "either",
 ]
+
+[[package]]
+name = "md5"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 [dependencies]
 anyhow = "1.0.93"
 itertools = "0.13.0"
+md5 = "0.7.0"

src/days.rs

@@ -2,7 +2,7 @@ pub mod d1;
 pub mod d2;
 pub mod d3;
 pub mod d4;
-// pub mod d5;
+pub mod d5;
 // pub mod d6;
 // pub mod d7;
 // pub mod d8;

src/days/d5.rs

@@ -0,0 +1,74 @@
+use crate::prelude::*;
+
+pub type I = &'static str;
+pub type O = String;
+
+fn _silver (data: I) -> O {
+    let mut s = s!("");
+
+    for i in 0.. {
+        let st = format!("{data}{i}");
+        let hash = md5::compute(st);
+
+        let repr = format!("{:x}", hash);
+
+        if repr.starts_with("00000") {
+            s.push_str(&repr[5..=5]);
+            if s.len() == 8 {
+                break;
+            }
+        }
+    }
+
+    s
+}
+
+fn _gold (data: I) -> O {
+    let mut s = ['\0'; 8];
+
+    for i in 0.. {
+        let st = format!("{data}{i}");
+        let hash = md5::compute(st);
+
+        let repr = format!("{:x}", hash);
+
+        if repr.starts_with("00000") {
+            let idx = (&repr[5..=5]).parse::<usize>().unwrap_or(usize::MAX);
+            let val = (&repr[6..=6]).chars().next().unwrap();
+
+            if idx < s.len() && s[idx] == '\0' {
+                s[idx] = val;
+            }
+
+            if s.iter().all(|&e| e != '\0') { break; }
+        }
+    }
+
+    s.into_iter().collect()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> I {
+        "abbhdwsy"
+    }
+
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(data);
+
+        assert_eq!(ans, s!("801b56a7"))
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(data);
+
+        assert_eq!(ans, s!("424a0197"))
+    }
+}