cant figure 19 out

day19/src/main.rs

@@ -36,42 +36,41 @@ fn main() {
 
     part1(conversions, &separate); // 576
 
-    main2();
+    _part2(conversions, formula);
+    // main2();
 }
 
-// fn _part2(conversions: &[(&str, &str)], formula: &str) {
-//     let mut rng = rand::rng();
+fn _part2(conversions: &[(&str, &str)], formula: &str) {
+    let mut rng = rand::rng();
 
-//     let mut rand_conversions = conversions.to_vec();
+    let mut rand_conversions = conversions.to_vec();
     // let mut old_conversion_count = 10000; // large
-//     let mut conversion_count;
+    let mut conversion_count;
 
-//     loop {
-//         conversion_count = 0;
-//         let mut formula_replaced = formula.to_string();
+    'outer: loop {
+        let mut current = formula.to_string();
 
-//         loop {
-//             let old_formula_replaced = formula_replaced.clone();
+        conversion_count = 0;
+        rand_conversions.shuffle(&mut rng);
 
-//             rand_conversions.shuffle(&mut rng);
+        while current != "e" {
+            let mut reduced_this_round = false;
+            for (short, long) in conversions {
+                if let Some(pos) = current.find(long) {
+                    conversion_count += 1;
+                    reduced_this_round = true;
+                    current.replace_range(pos..pos + long.len(), short);
+                    break;
+                }
+            }
 
-//             for (short, long) in conversions {
-//                 if formula_replaced.contains(long) {
-//                     conversion_count += 1;
-//                 }
-
-//                 formula_replaced = replace_any(formula_replaced, long, short, &mut rng);
-//             }
-//             if formula_replaced == old_formula_replaced {
-//                 break;
-//             }
-//         }
-//         if conversion_count < old_conversion_count {
-//             println!("{conversion_count}");
-//             old_conversion_count = conversion_count;
-//         }
-//     }
-// }
+            if !reduced_this_round {
+                continue 'outer;
+            }
+        }
+        println!("{conversion_count}");
+    }
+}
 
 // fn replace_any(input: String, long: &str, short: &str, rng: &mut ThreadRng) -> String {
 //     let haystack: Vec<_> = input.chars().collect();
@@ -146,6 +145,8 @@ fn part1(conversions: &[(&str, &str)], formula: &[String]) {
 
 use std::fs;
 
+use rand::seq::SliceRandom;
+
 /// A single replacement rule as it appears in the puzzle input: `from => to`.
 struct Rule {
     from: String,