AoC 2025 Day 3 - java

Author: pareronia

README.md

@@ -9,7 +9,7 @@
 | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2025_01.py) | [✓](src/main/python/AoC2025_02.py) | [✓](src/main/python/AoC2025_03.py) |  |  |  |  |  |  |  |  |  |
-| java | [✓](src/main/java/AoC2025_01.java) | [✓](src/main/java/AoC2025_02.java) |  |  |  |  |  |  |  |  |  |  |
+| java | [✓](src/main/java/AoC2025_01.java) | [✓](src/main/java/AoC2025_02.java) | [✓](src/main/java/AoC2025_03.java) |  |  |  |  |  |  |  |  |  |
 | bash | [✓](src/main/bash/AoC2025_01.sh) | [✓](src/main/bash/AoC2025_02.sh) | [✓](src/main/bash/AoC2025_03.sh) |  |  |  |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2025@ -->
 

src/main/java/AoC2025_03.java

@@ -0,0 +1,73 @@
+import com.github.pareronia.aoc.solution.Sample;
+import com.github.pareronia.aoc.solution.Samples;
+import com.github.pareronia.aoc.solution.SolutionBase;
+
+import java.util.List;
+
+@SuppressWarnings({"PMD.ClassNamingConventions", "PMD.NoPackage"})
+public final class AoC2025_03 extends SolutionBase<List<String>, Long, Long> {
+
+    private AoC2025_03(final boolean debug) {
+        super(debug);
+    }
+
+    public static AoC2025_03 create() {
+        return new AoC2025_03(false);
+    }
+
+    public static AoC2025_03 createDebug() {
+        return new AoC2025_03(true);
+    }
+
+    @Override
+    protected List<String> parseInput(final List<String> inputs) {
+        return inputs;
+    }
+
+    private long solveLine(final String line, final int digits) {
+        int pos = 0;
+        final StringBuilder sb = new StringBuilder();
+        for (int i = digits; i > 0; i--) {
+            char best = '0';
+            for (int j = pos; j < line.length() - i + 1; j++) {
+                final char val = line.charAt(j);
+                if (val > best) {
+                    best = val;
+                    pos = j + 1;
+                }
+            }
+            sb.append(best);
+        }
+        return Long.parseLong(sb.toString());
+    }
+
+    private long solve(final List<String> lines, final int digits) {
+        return lines.stream().mapToLong(line -> solveLine(line, digits)).sum();
+    }
+
+    @Override
+    public Long solvePart1(final List<String> lines) {
+        return this.solve(lines, 2);
+    }
+
+    @Override
+    public Long solvePart2(final List<String> lines) {
+        return this.solve(lines, 12);
+    }
+
+    @Samples({
+        @Sample(method = "part1", input = TEST, expected = "357"),
+        @Sample(method = "part2", input = TEST, expected = "3121910778619"),
+    })
+    public static void main(final String[] args) throws Exception {
+        create().run();
+    }
+
+    private static final String TEST =
+            """
+            987654321111111
+            811111111111119
+            234234234234278
+            818181911112111
+            """;
+}