Advent 2025 Day 2 Part 2

advent_of_code_2025/src/day2/part2.rs

@@ -14,14 +14,26 @@ pub fn solve(input: &str) {
 
     for range in ranges {
         for idx in range.start..range.end {
-            let as_str = format!("{idx}");
+            let id = format!("{idx}");
+            let pattern_max_len = id.len() / 2;
+            // println!("id: {id}, len: {}, pattern_max_len: {pattern_max_len}", id.len());
+            
+            for pattern_len in 1..=pattern_max_len {
+                if id.len() % pattern_len != 0 {
+                    continue;
+                }
+                
+                let repeats = id.len() / pattern_len;
+                let pattern = id[..pattern_len].repeat(repeats);
 
-            if as_str.len() % 2 == 0  && as_str[..as_str.len() / 2] == as_str[as_str.len() / 2..] {
+                if pattern == id {
-                // println!("invalid found: {as_str}");
+                    sum_of_invalids += idx;
-                sum_of_invalids += idx;
+                    // println!("invalid pattern found: {id} (pattern: {})", &pattern[..pattern_len]);
+                    break
+                }
             }
         }
     }
 
-    println!("Part 1: {sum_of_invalids}");
+    println!("Part 2: {sum_of_invalids}");
 }

advent_of_code_2025/src/main.rs

@@ -1,5 +1,5 @@
 use paste::paste;
 mod utility;
 
-solve_day!{1}
+solve_day!{2}
-// test_day!{1}
+// test_day!{2}