From 98e6f49561f492d026a6aba7b49064e7c544a964 Mon Sep 17 00:00:00 2001
From: Xavier Morel <morelx42@gmail.com>
Date: Tue, 19 Nov 2024 15:46:42 +0100
Subject: [PATCH] feat: add day 5 part 2

---
 src/bin/05.rs | 76 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 45 insertions(+), 31 deletions(-)

diff --git a/src/bin/05.rs b/src/bin/05.rs
index 671f2ba..e260384 100644
--- a/src/bin/05.rs
+++ b/src/bin/05.rs
@@ -1,41 +1,55 @@
 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
-    }
+fn get_valid_digests(prefix: &str) -> impl Iterator<Item = String> + '_ {
+    (1..)
+        .flat_map(move |x| {
+            let data = format!("{}{:?}", prefix, x);
+            let digest = format!("{:x}", md5::compute(data));
+            if digest.starts_with("00000") {
+                Some(digest)
+            } else {
+                None
+            }
+        })
+        // .filter(|x| x.is_some())
+        // .map(|x| x.unwrap())
 }
 
-
 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())
+    let input = input.strip_suffix("\n").unwrap_or(input);
+    let res: String = get_valid_digests(input)
+        .take(8)
+        .map(|x| x.chars().nth(5).unwrap())
+        .collect();
+    Some(res)
 }
 
 pub fn part_two(input: &str) -> Option<String> {
-    None
+    let input = input.strip_suffix("\n").unwrap_or(input);
+    let res: [Option<char>; 8] = [None; 8];
+    let end_res: String = get_valid_digests(input)
+        .scan(res, |state, digest| {
+            let char_to_put: char = digest.chars().nth(6).unwrap();
+            if let Ok(pos_nth) = String::from(digest.chars().nth(5).unwrap()).parse::<usize>() {
+                if pos_nth < 8 && state[pos_nth].is_none() {
+                    state[pos_nth] = Some(char_to_put);
+                    // for c in &mut *state {
+                    //     if let Some(c) = c {
+                    //         print!("{}", c);
+                    //     } else {
+                    //         print!("_");
+                    //     }
+                    // }
+                    // println!(" - put {} in {:?} - digest {}", char_to_put, pos_nth, digest);
+                }
+            }
+            Some(*state)  // .clone())
+        })
+        .filter(|s| s.iter().all(|x| x.is_some()))
+        .take(1)
+        .flat_map(|r| r.iter().map(|x| x.unwrap()).collect::<Vec<_>>())
+        .collect();
+    Some(end_res)
 }
 
 #[cfg(test)]
@@ -51,6 +65,6 @@ mod tests {
     #[test]
     fn test_part_two() {
         let result = part_two(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some("05ace8e3".into()));
     }
 }