aoc 2024 day 4 refactor

TheCK · Dec 4, 2024 · a03312f · a03312f
1 parent 1600e5b
commit a03312f
Showing 1 changed file with 27 additions and 69 deletions.
diff --git a/adventofcode/src/main/java/org/ck/adventofcode/year2024/Day04.java b/adventofcode/src/main/java/org/ck/adventofcode/year2024/Day04.java
@@ -1,6 +1,7 @@
 package org.ck.adventofcode.year2024;
 
 import java.util.*;
+import java.util.function.IntFunction;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import org.ck.adventofcode.util.AOCSolution;
@@ -17,96 +18,53 @@
     url = "https://adventofcode.com/2024/day/4#part2",
     category = "2024")
 public class Day04 extends AOCSolution {
+  private static final String XMAS = "XMAS";
+  private static final String SAMX = "SAMX";
+  private static final String XMAS_OTHERS = "X.{%1$d}M.{%1$d}A.{%1$d}S";
+  private static final String SAMX_OTHERS = "S.{%1$d}A.{%1$d}M.{%1$d}X";
   private static final String X_MAS_PATTERN =
-      "([MS]).([MS]).{%1$d}A.{%1$d}((?!\\2)[MS]).((?!\\1)[MS])";
+      "([MS])[^\\n]([MS]).{%1$d}A.{%1$d}((?!\\2)[MS]).((?!\\1)[MS])";
 
   @Override
   protected void runPartOne(final Scanner in) {
-    List<String> grid = new ArrayList<>();
-
-    while (in.hasNextLine()) {
-      grid.add(in.nextLine());
-    }
-
-    long count = 0;
-
-    for (int i = 0; i < grid.size(); ++i) {
-      for (int j = 0; j < grid.get(i).length(); ++j) {
-        if (j < grid.get(i).length() - 3 && "XMAS".equals(grid.get(i).substring(j, j + 4))) {
-          ++count;
-        }
-        if (j < grid.get(i).length() - 3 && "SAMX".equals(grid.get(i).substring(j, j + 4))) {
-          ++count;
-        }
-        if (i < grid.size() - 3
-            && grid.get(i).charAt(j) == 'X'
-            && grid.get(i + 1).charAt(j) == 'M'
-            && grid.get(i + 2).charAt(j) == 'A'
-            && grid.get(i + 3).charAt(j) == 'S') {
-          ++count;
-        }
-        if (i < grid.size() - 3
-            && grid.get(i).charAt(j) == 'S'
-            && grid.get(i + 1).charAt(j) == 'A'
-            && grid.get(i + 2).charAt(j) == 'M'
-            && grid.get(i + 3).charAt(j) == 'X') {
-          ++count;
-        }
-        if (i < grid.size() - 3 && j < grid.get(i).length() - 3) {
-          if (grid.get(i).charAt(j) == 'X'
-              && grid.get(i + 1).charAt(j + 1) == 'M'
-              && grid.get(i + 2).charAt(j + 2) == 'A'
-              && grid.get(i + 3).charAt(j + 3) == 'S') {
-            ++count;
-          }
-          if (grid.get(i).charAt(j) == 'S'
-              && grid.get(i + 1).charAt(j + 1) == 'A'
-              && grid.get(i + 2).charAt(j + 2) == 'M'
-              && grid.get(i + 3).charAt(j + 3) == 'X') {
-            ++count;
-          }
-          if (grid.get(i + 3).charAt(j) == 'X'
-              && grid.get(i + 2).charAt(j + 1) == 'M'
-              && grid.get(i + 1).charAt(j + 2) == 'A'
-              && grid.get(i).charAt(j + 3) == 'S') {
-            ++count;
-          }
-          if (grid.get(i + 3).charAt(j) == 'S'
-              && grid.get(i + 2).charAt(j + 1) == 'A'
-              && grid.get(i + 1).charAt(j + 2) == 'M'
-              && grid.get(i).charAt(j + 3) == 'X') {
-            ++count;
-          }
-        }
-      }
-    }
-
-    print(count);
+    run(
+        in,
+        l ->
+            List.of(
+                Pattern.compile(XMAS),
+                Pattern.compile(SAMX),
+                Pattern.compile(XMAS_OTHERS.formatted(l), Pattern.DOTALL),
+                Pattern.compile(SAMX_OTHERS.formatted(l), Pattern.DOTALL),
+                Pattern.compile(XMAS_OTHERS.formatted(l + 1), Pattern.DOTALL),
+                Pattern.compile(SAMX_OTHERS.formatted(l + 1), Pattern.DOTALL),
+                Pattern.compile(XMAS_OTHERS.formatted(l - 1), Pattern.DOTALL),
+                Pattern.compile(SAMX_OTHERS.formatted(l - 1), Pattern.DOTALL)));
   }
 
   @Override
   protected void runPartTwo(final Scanner in) {
-    run(in);
+    run(in, l -> List.of(Pattern.compile(X_MAS_PATTERN.formatted(l - 1), Pattern.DOTALL)));
   }
 
-  private void run(final Scanner in) {
+  private void run(final Scanner in, IntFunction<List<Pattern>> getPatterns) {
     final List<String> grid = new ArrayList<>();
 
     while (in.hasNextLine()) {
       grid.add(in.nextLine());
     }
 
+    final String text = String.join("\n", grid);
     final int lineLength = grid.getFirst().length();
-    final Pattern pattern = Pattern.compile(X_MAS_PATTERN.formatted(lineLength - 2));
-    final Matcher matcher = pattern.matcher(String.join("", grid));
+    final List<Pattern> patterns = getPatterns.apply(lineLength);
 
     long count = 0;
-    int start = 0;
+    for (Pattern pattern : patterns) {
+      final Matcher matcher = pattern.matcher(text);
 
-    while (matcher.find(start)) {
-      start = matcher.start() + 1;
+      int start = 0;
+      while (matcher.find(start)) {
+        start = matcher.start() + 1;
 
-      if (matcher.start() % lineLength < lineLength - 2) {
         ++count;
       }
     }