feat: add day 5 part 1

data/examples/05.txt

@@ -0,0 +1 @@
+abc

src/bin/05.rs

@@ -0,0 +1,56 @@
+advent_of_code::solution!(5);
+
+use md5;
+
+
+fn get_char(data: &str) -> Option<char> {
+    let digest = format!("{:x}", md5::compute(data));
+    if digest.starts_with("00000") {
+        digest.chars().nth(5)
+    } else {
+        None
+    }
+}
+
+
+pub fn part_one(input: &str) -> Option<String> {
+    let input = input
+        .strip_suffix("\n")
+        .unwrap_or(input);
+    let mut res: Vec<char> = Vec::new();    
+    for x in 1.. {
+        if let Some(chr) = get_char(format!("{}{}", input, x).as_str()) {
+            println!("Found {:?} at index {:?}", chr, x);
+            res.push(chr);
+            if res.len() == 8 {
+                break;
+            }
+        }
+        if x > 100_000_000 {
+            break;
+        }
+    }
+
+    Some(res.into_iter().collect())
+}
+
+pub fn part_two(input: &str) -> Option<String> {
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some("18f47a30".into()));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}