Day 5 - Played arround with iterators

src/day5/main.rs

@@ -20,65 +20,93 @@ impl Extend<RangeInclusive<u64>> for RangeInclusive<u64> {
     }
 }
 
+struct ReduceUtilFold<Return, Over: Iterator, P>
+where
+    P: FnMut(Over::Item, Option<Over::Item>) -> (Option<Over::Item>, Option<Return>),
+{
+    over: Over,
+    cur: Option<Over::Item>,
+    perdicate: P,
+}
+
+impl<Return, Over: Iterator, P> ReduceUtilFold<Return, Over, P>
+where
+    P: FnMut(Over::Item, Option<Over::Item>) -> (Option<Over::Item>, Option<Return>),
+{
+    fn new(over: Over, perdicate: P) -> ReduceUtilFold<Return, Over, P> {
+        ReduceUtilFold {
+            over,
+            perdicate,
+            cur: None,
+        }
+    }
+}
+
+impl<
+    Return,
+    Over: Iterator,
+    P: FnMut(Over::Item, Option<Over::Item>) -> (Option<Over::Item>, Option<Return>),
+> Iterator for ReduceUtilFold<Return, Over, P>
+{
+    type Item = Return;
+    fn next(&mut self) -> Option<Return> {
+        let mut first: Option<Over::Item> = None;
+        std::mem::swap(&mut first, &mut self.cur);
+        let mut first = first.or_else(|| self.over.next())?;
+        loop {
+            let (cont, ret) = (self.perdicate)(first, self.over.next());
+            if ret.is_some() {
+                self.cur = cont;
+                return ret;
+            }
+            first = cont?;
+        }
+    }
+}
+
 fn main() -> Result<()> {
     let text = fs::read_to_string("src/day5/act.txt")?;
 
-    let mut valid_ids: Vec<Option<RangeInclusive<u64>>> = text
+    let mut valid_ids: Vec<RangeInclusive<u64>> = text
         .split("\n")
         .take_while(|s| s.len() > 0)
         .map(|s| {
             let mut v = s.split('-').map(|a| a.parse().unwrap());
             let start: u64 = v.next().unwrap();
             let end: u64 = v.next().unwrap();
-            return Some(start..=end);
+            return start..=end;
         })
         .collect();
+    valid_ids.sort_by(|a, b| a.start().cmp(b.start()));
 
-    let mut expanded = true;
-    while expanded {
-        expanded = false;
-        for i in 0..valid_ids.len() {
-            let range_to_extend = &valid_ids[i];
-            if range_to_extend.is_some() {
-                let mut range_to_extend = valid_ids[i].as_ref().unwrap().clone();
-                for j in (i + 1)..valid_ids.len() {
-                    if let Some(maybe_comp) = valid_ids[j].as_ref() {
-                        if let Some(extended) = range_to_extend.extend(&maybe_comp) {
-                            println!(
-                                "{:?} expanded by {:?} into {:?}",
-                                range_to_extend, maybe_comp, extended
-                            );
-                            expanded = true;
-                            range_to_extend = extended;
-                            valid_ids[j] = None;
-                        }
-                    }
-                }
-                valid_ids[i] = Some(range_to_extend);
+    let valid_ids: Vec<RangeInclusive<u64>> = ReduceUtilFold::new(valid_ids.into_iter(), |a, b| {
+        if let Some(b) = b {
+            if let Some(extended) = a.extend(&b) {
+                (Some(extended), None)
+            } else {
+                (Some(b), Some(a))
             }
+        } else {
+            (None, Some(a))
         }
-        valid_ids = valid_ids.into_iter().filter(|a| a.is_some()).collect();
-    }
+    })
+    .collect();
 
-    let valid_ids = valid_ids.into_iter().map(|a| a.unwrap());
-
-    valid_ids.clone().for_each(|a| println!("{:?}", a));
-
-    let ids_to_check = text
+    let fresh_ids = text
         .split("\n")
         .skip_while(|s| s.len() > 0)
         .skip(1)
         .filter(|s| s.len() > 0)
         .fold(0, |sum, line| {
             let i: u64 = line.parse().unwrap();
-            sum + valid_ids.clone().any(|range| range.contains(&i)) as i64
+            sum + valid_ids.iter().any(|range| range.contains(&i)) as i64
         });
 
-    let num_valid_ids = valid_ids.fold(0, |sum, range_id| {
+    let num_valid_ids = valid_ids.iter().fold(0, |sum, range_id| {
         sum + range_id.end() - range_id.start() + 1
     });
 
-    println!("sol1: {}! sol2: {}", ids_to_check, num_valid_ids);
+    println!("sol1: {}! sol2: {}", fresh_ids, num_valid_ids);
 
     Ok(())
 }