day 2 part 1

main.java.tmpl

@@ -11,6 +11,8 @@ public class Day00 {
 
     private static void part1() {
         try (Scanner scanner = new Scanner(new FileReader("resources/inputs/00/input"))) {
+            StringBuilder sb = new StringBuilder();
+
             while (scanner.hasNextLine()) {
                 sb.append(scanner.nextLine());
                 sb.append("\n");
@@ -24,6 +26,8 @@ public class Day00 {
 
     private static void part2() {
         try (Scanner scanner = new Scanner(new FileReader("resources/inputs/00/input"))) {
+            StringBuilder sb = new StringBuilder();
+
             while (scanner.hasNextLine()) {
                 sb.append(scanner.nextLine());
                 sb.append("\n");

src/Day02.java

@@ -0,0 +1,74 @@
+package src;
+
+import java.io.FileReader;
+import java.util.Scanner;
+
+public class Day02 {
+    public static void main(String[] args) {
+        part1();
+        // part2();
+    }
+
+    private static void part1() {
+        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("-");
+                String start = range[0];
+                long end = Long.parseLong(range[1]);
+                if (isInvalid(start)) {
+                    sum += Long.parseLong(start);
+                }
+                start = permute(start);
+                while (Long.parseLong(start) <= end) {
+                    sum += Long.parseLong(start);
+                    start = permute(start);
+                }
+            }
+            System.out.println(sum);
+        } catch (Exception e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    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");
+            }
+            String input = sb.toString();
+            System.out.println(input);
+        } catch (Exception e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    private static boolean isInvalid(String id) {
+        if (id.length() % 2 != 0) {
+            // 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;
+    }
+
+    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));
+        }
+        long head = Long.parseLong(str.subSequence(0, str.length() / 2).toString());
+        long tail = Long.parseLong(str.subSequence(str.length() / 2, str.length()).toString());
+        if (tail < head) {
+            return String.valueOf(head) + String.valueOf(head);
+        }
+        head++;
+        return String.valueOf(head) + String.valueOf(head);
+    }
+}