ah, cephalapod math

2025-12-06 08:36:05 -05:00
parent e79e352d7a
commit 8804c70a53
1 changed files with 107 additions and 0 deletions
--- a/src/Day06.java
+++ b/src/Day06.java
@@ -0,0 +1,107 @@
+package src;
+
+import java.io.FileReader;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+
+public class Day06 {
+    public static void main(String[] args) {
+        Instant start = Instant.now();
+        part1();
+        Instant middle = Instant.now();
+        part2();
+        Instant end = Instant.now();
+        IO.println("part 1: " + Duration.between(start, middle).toMillis() + " ms");
+        IO.println("part 2: " + Duration.between(middle, end).toMillis() + " ms");
+    }
+
+    private static void part1() {
+        try (Scanner scanner = new Scanner(new FileReader("resources/inputs/06/input"))) {
+            List<List<Integer>> inputs = new java.util.ArrayList<>();
+            List<String> operations = new java.util.ArrayList<>();
+            while (scanner.hasNextLine()) {
+                String row = scanner.nextLine();
+                if (row.contains("+")) {
+                    operations = Arrays.asList(row.split("\s+"));
+                } else {
+                    List<Integer> numbers = Arrays.asList(row.split("\s+")).stream().map(Integer::parseInt).toList();
+                    inputs.add(numbers);
+                }
+            }
+            Long grandTotal = 0L;
+            for (int i = 0; i < operations.size(); i++) {
+                String operation = operations.get(i);
+                Long total = 0L;
+                for (List<Integer> input : inputs) {
+                    Integer number = input.get(i);
+                    switch (operation) {
+                        case "+" -> total += number;
+                        case "*" -> {
+                            if (total == 0) {
+                                total = 1L;
+                            }
+                            total *= number;
+                        }
+                    }
+                }
+                grandTotal += total;
+            }
+            IO.println(grandTotal);
+        } catch (Exception e) {
+            IO.println(e.getMessage());
+        }
+    }
+
+    private static void part2() {
+        try (Scanner scanner = new Scanner(new FileReader("resources/inputs/06/input"))) {
+            String operations = "";
+            List<String> numbers = new java.util.ArrayList<>();
+            while (scanner.hasNextLine()) {
+                String row = scanner.nextLine();
+                if (row.contains("+")) {
+                    operations = row;
+                } else {
+                    numbers.add(row);
+                }
+            }
+            Long grandTotal = 0L;
+            Long total = 0L;
+            char currentOp = ' ';
+            for (int i = 0; i < operations.length(); i++) {
+                char operation = operations.charAt(i);
+                if (operation != ' ') {
+                    currentOp = operation;
+                }
+                StringBuilder sb = new StringBuilder();
+                for (String row : numbers) {
+                    sb.append(row.charAt(i));
+                }
+                String column = sb.toString().trim();
+                if (column.isBlank()) {
+                    grandTotal += total;
+                    total = 0L;
+                } else {
+                    Long number = Long.parseLong(column);
+                    switch (currentOp) {
+                        case '+' -> total += number;
+                        case '*' -> {
+                            if (total == 0) {
+                                total = 1L;
+                            }
+                            total *= number;
+                        }
+                    }
+                }
+            }
+            // catch last problem
+            grandTotal += total;
+            // and done
+            IO.println(grandTotal);
+        } catch (Exception e) {
+            IO.println(e.getMessage());
+        }
+    }
+}