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FlashkyFlashky
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feat: solve day 6
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6 files changed

+163
-12
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‎README.md‎

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@@ -8,7 +8,7 @@
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- [Day 3 - Mull It Over](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day03)
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- [Day 4 - Ceres Search](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day04)
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- [Day 5 - Print Queue](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day05)
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- [Day 6](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day06)
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- [Day 6 - Guard Gallivant](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day06)
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- [Day 7](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day07)
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- [Day 8](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day08)
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- [Day 9](https://github.com/Flashky/advent-of-code-2024/tree/master/src/main/java/com/adventofcode/flashk/day09)

‎pom.xml‎

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@@ -68,8 +68,14 @@
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<artifactId>commons-math3</artifactId>
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<version>3.6.1</version>
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</dependency>
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<dependency>
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<groupId>org.jetbrains</groupId>
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<artifactId>annotations</artifactId>
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<version>13.0</version>
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<scope>compile</scope>
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</dependency>
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</dependencies>
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</dependencies>
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<build>
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<plugins>

‎src/main/java/com/adventofcode/flashk/day06/GuardGallivant.java‎

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package com.adventofcode.flashk.day06;
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import com.adventofcode.flashk.common.Vector2;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Set;
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public class GuardGallivant {
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private static final char OBSTACLE = '#';
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private static final char OBSTRUCTION = 'O';
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private static final char UNVISITED = '.';
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private static final char VISITED = 'X';
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private final char[][] map;
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private final int rows;
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private final int cols;
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private GuardState initialGuardState;
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private Set<GuardState> guardStates = new HashSet<>();
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public GuardGallivant(char[][] inputs) {
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this.map = inputs;
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this.rows = inputs.length;
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this.cols = inputs[0].length;
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for(int row = 0; row < rows; row++) {
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for(int col = 0; col < cols; col++) {
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if(inputs[row][col] == '^') {
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initialGuardState = new GuardState(new Vector2(col,row), new Vector2(0,-1));
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guardStates.add(initialGuardState);
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break;
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}
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}
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}
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}
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public long solveA() {
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simulateGuardMovement();
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return guardStates.stream().map(GuardState::pos).distinct().count();
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}
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public long solveB() {
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// Obtain first execution guard information
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simulateGuardMovement();
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List<Vector2> possibleObstructionPositions = guardStates.stream().map(GuardState::pos)
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.distinct().filter(pos -> !pos.equals(initialGuardState.pos())).toList();
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resetMap();
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// Search for loops
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long loopCount = 0;
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for(Vector2 obstructionPos : possibleObstructionPositions) {
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map[obstructionPos.getY()][obstructionPos.getX()] = OBSTRUCTION;
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if(simulateGuardMovement()) {
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loopCount++;
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}
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resetMap();
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}
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return loopCount;
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}
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private boolean simulateGuardMovement() {
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boolean isLoop = false;
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Vector2 guardPos = initialGuardState.pos();
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Vector2 guardDir = initialGuardState.dir();
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Vector2 nextPos;
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do {
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nextPos = Vector2.transform(guardPos,guardDir);
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if(canMove(nextPos)) {
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guardPos = nextPos;
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GuardState guardState = new GuardState(guardPos, guardDir);
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if(guardStates.contains(guardState)) {
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isLoop = true;
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} else {
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guardStates.add(guardState);
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map[nextPos.getY()][nextPos.getX()] = VISITED;
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}
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} else {
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guardDir.rotateLeft();
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}
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} while(!isOutOfBounds(nextPos.getY(), nextPos.getX()) && !isLoop);
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return isLoop;
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}
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private boolean canMove(Vector2 nextPos) {
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if(isOutOfBounds(nextPos.getY(), nextPos.getX())) {
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return false;
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}
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return map[nextPos.getY()][nextPos.getX()] != OBSTACLE && map[nextPos.getY()][nextPos.getX()] != OBSTRUCTION;
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}
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private boolean isOutOfBounds(int row, int col) {
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return row < 0 || row >= rows || col < 0 || col >= cols;
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}
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private void resetMap() {
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guardStates = new HashSet<>();
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guardStates.add(initialGuardState);
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for(int row = 0; row < rows; row++) {
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for(int col = 0; col < cols; col++) {
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if(map[row][col] != OBSTACLE) {
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map[row][col] = UNVISITED;
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}
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}
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}
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}
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}

‎src/main/java/com/adventofcode/flashk/day06/GuardState.java‎

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package com.adventofcode.flashk.day06;
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import com.adventofcode.flashk.common.Vector2;
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public record GuardState(Vector2 pos, Vector2 dir) {
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public Vector2 pos() {
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return new Vector2(pos);
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}
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public Vector2 dir() {
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return new Vector2(dir);
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}
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}

‎src/test/java/com/adventofcode/flashk/day06/Day06Test.java‎

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@@ -19,9 +19,10 @@
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import com.adventofcode.flashk.common.test.utils.Timer;
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import com.adventofcode.flashk.common.test.utils.Input;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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@DisplayName(TestDisplayName.DAY_06)
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@TestMethodOrder(OrderAnnotation.class)
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@Disabled // TODO Remove comment when implemented
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public class Day06Test extends PuzzleTest {
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2728
private final static String INPUT_FOLDER = TestFolder.DAY_06;
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System.out.print("1 | sample | ");
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// Read input file
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List<String> inputs = Input.readStringLines(INPUT_FOLDER, TestFilename.INPUT_FILE_SAMPLE);
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char[][] inputs = Input.read2DCharArray(INPUT_FOLDER, TestFilename.INPUT_FILE_SAMPLE);
47+
GuardGallivant guardGallivant = new GuardGallivant(inputs);
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assertEquals(41,guardGallivant.solveA());
4750
}
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4952
@Test
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5659
System.out.print("1 | input | ");
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5861
// Read input file
59-
List<String> inputs = Input.readStringLines(INPUT_FOLDER, TestFilename.INPUT_FILE);
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char[][] inputs = Input.read2DCharArray(INPUT_FOLDER, TestFilename.INPUT_FILE);
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GuardGallivant guardGallivant = new GuardGallivant(inputs);
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assertEquals(5269,guardGallivant.solveA());
6166
}
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6368
@Test
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7075
System.out.print("2 | sample | ");
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// Read input file
73-
List<String> inputs = Input.readStringLines(INPUT_FOLDER, TestFilename.INPUT_FILE_SAMPLE);
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char[][] inputs = Input.read2DCharArray(INPUT_FOLDER, TestFilename.INPUT_FILE_SAMPLE);
79+
GuardGallivant guardGallivant = new GuardGallivant(inputs);
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assertEquals(6,guardGallivant.solveB());
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}
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@Test
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8491
System.out.print("2 | input | ");
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// Read input file
87-
List<String> inputs = Input.readStringLines(INPUT_FOLDER, TestFilename.INPUT_FILE);
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char[][]inputs = Input.read2DCharArray(INPUT_FOLDER, TestFilename.INPUT_FILE);
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GuardGallivant guardGallivant = new GuardGallivant(inputs);
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assertEquals(1957,guardGallivant.solveB());
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}
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}

‎src/test/resources/inputs‎

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