give up and do part 2 via a for loop

main.java.tmpl

@@ -18,9 +18,9 @@ public class Day00 {
                 sb.append("\n");
             }
             String input = sb.toString();
-            System.out.println(input);
+            IO.println(input);
         } catch (Exception e) {
-            System.out.println(e.getMessage());
+            IO.println(e.getMessage());
         }
     }
 
@@ -33,9 +33,9 @@ public class Day00 {
                 sb.append("\n");
             }
             String input = sb.toString();
-            System.out.println(input);
+            IO.println(input);
         } catch (Exception e) {
-            System.out.println(e.getMessage());
+            IO.println(e.getMessage());
         }
     }
 }

src/Day02.java

@@ -6,7 +6,7 @@ import java.util.Scanner;
 public class Day02 {
     public static void main(String[] args) {
         part1();
-        // part2();
+        part2();
     }
 
     private static void part1() {
@@ -26,24 +26,31 @@ public class Day02 {
                     start = permute(start);
                 }
             }
-            System.out.println(sum);
+            IO.println(sum);
         } catch (Exception e) {
-            System.out.println(e.getMessage());
+            IO.println(e.getMessage());
         }
     }
 
+    // fine, we'll just iterate the whole range
+    // can probably do this by bitshifting instead of long<->string conversions
     private static void part2() {
-        try (Scanner scanner = new Scanner(new FileReader("resources/inputs/02/input"))) {
-            StringBuilder sb = new StringBuilder();
-
-            while (scanner.hasNextLine()) {
-                sb.append(scanner.nextLine());
-                sb.append("\n");
+        try (Scanner scanner = new Scanner(new FileReader("resources/inputs/02/input")).useDelimiter(",")) {
+            long sum = 0L;
+            while (scanner.hasNext()) {
+                String input = scanner.next().trim();
+                String[] range = input.split("-");
+                long start = Long.parseLong(range[0]);
+                long end = Long.parseLong(range[1]);
+                for (long i = start; i <= end; i++) {
+                    if (hasPattern(String.valueOf(i))) {
+                        sum += i;
+                    }
+                }
             }
-            String input = sb.toString();
-            System.out.println(input);
+            IO.println(sum);
         } catch (Exception e) {
-            System.out.println(e.getMessage());
+            IO.println(e.getMessage());
         }
     }
 
@@ -52,23 +59,32 @@ public class Day02 {
             // odd length, can't have a repeated pair
             return false;
         }
-        return CharSequence.compare(
-                id.subSequence(0, id.length() / 2),
-                id.subSequence(id.length() / 2, id.length())) == 0;
+        return id.substring(0, id.length() / 2) == id.substring(id.length() / 2);
     }
 
     private static String permute(String str) {
         if (str.length() % 2 != 0) {
             // in this case, we need to get to a even-length string
-            return String.valueOf((int) Math.pow(10, str.length() / 2))
-                    + String.valueOf((int) Math.pow(10, str.length() / 2));
+            return String.valueOf((long) Math.pow(10, str.length() / 2))
+                    + String.valueOf((long) Math.pow(10, str.length() / 2));
         }
-        long head = Long.parseLong(str.subSequence(0, str.length() / 2).toString());
-        long tail = Long.parseLong(str.subSequence(str.length() / 2, str.length()).toString());
+        long head = Long.parseLong(str.substring(0, str.length() / 2));
+        long tail = Long.parseLong(str.substring(str.length() / 2, str.length()));
         if (tail < head) {
             return String.valueOf(head) + String.valueOf(head);
         }
         head++;
         return String.valueOf(head) + String.valueOf(head);
     }
+
+    // don't need regexes, at least
+    private static boolean hasPattern(String str) {
+        for (int patternLength = 1; patternLength <= str.length() / 2; patternLength++) {
+            String candidate = str.substring(0, patternLength).repeat(str.length() / patternLength);
+            if (candidate.equals(str)) {
+                return true;
+            }
+        }
+        return false;
+    }
 }