8000 day 9 · AbdulRehman56/AdventOfCode-Java@960b152 · GitHub
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SimonBaarsSimonBaars
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day 9
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lines changed

2 files changed

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lines changed

‎src/main/java/com/sbaars/adventofcode/network/FetchInput.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@ public FetchInput() {
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}
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public static void main(String[] args) {
32-
new FetchInput().retrieveDay("8", "2024");
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new FetchInput().retrieveDay("9", "2024");
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}
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private void retrieveDay(String day, String year) {

‎src/main/java/com/sbaars/adventofcode/year24/days/Day9.java

Lines changed: 99 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,19 @@
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import com.sbaars.adventofcode.year24.Day2024;
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import static com.sbaars.adventofcode.util.AoCUtils.zipWithIndex;
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import static java.lang.Integer.parseInt;
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import static java.util.Collections.reverseOrder;
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import static java.util.stream.IntStream.range;
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import static java.util.stream.IntStream.rangeClosed;
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import java.util.*;
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import java.util.concurrent.atomic.AtomicBoolean;
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import java.util.concurrent.atomic.AtomicInteger;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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public class Day9 extends Day2024 {
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public Day9() {
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super(9);
@@ -11,13 +24,97 @@ public static void main(String[] args) {
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new Day9().printParts();
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}
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record Data(int start, int end, int length) {
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Data(int start) {
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this(start, start, 1);
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}
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Data updateEnd(int end) {
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return new Data(this.start, end, end - this.start + 1);
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}
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}
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@Override
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public Object part1() {
16-
return "";
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var disk = disk();
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compactDisk(disk);
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return checksum(disk);
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}
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@Override
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public Object part2() {
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return "";
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var disk = disk();
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var files = parseData(disk);
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moveFiles(disk, files);
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return checksum(disk);
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}
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private List<Integer> disk() {
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AtomicInteger id = new AtomicInteger(0);
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AtomicBoolean b = new AtomicBoolean(true);
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return dayStream("").filter(s -> !s.isBlank()).map(c -> parseInt(c)).flatMap(length -> {
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int value = b.getAndSet(!b.get()) ? id.getAndIncrement() : -1;
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return Stream.generate(() -> value).limit(length);
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}).collect(Collectors.toCollection(ArrayList::new));
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}
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private void compactDisk(List<Integer> disk) {
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while (disk.indexOf(-1) != -1) {
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int rightBlock;
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do {
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rightBlock = disk.remove(disk.size() - 1);
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} while (rightBlock == -1);
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disk.set(disk.indexOf(-1), rightBlock);
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}
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}
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private Map<Integer, Data> parseData(List<Integer> disk) {
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return zipWithIndex(disk.stream()).filter(b -> b.e() != -1).reduce(new HashMap<Integer, Data>(), (map, b) -> {
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map.merge(b.e(), new Data(b.i()), (d1, d2) -> d1.updateEnd(b.i()));
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return map;
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}, (a, b) -> {
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a.putAll(b);
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return a;
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});
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}
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private void moveFiles(List<Integer> disk, Map<Integer, Data> files) {
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files.keySet().stream().sorted(reverseOrder()).forEach(id -> {
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Data d = files.get(id);
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int l = d.length();
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int file = findFile(disk, l, d.start());
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if (file != -1) {
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clearOldPositions(disk, d);
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setNewPositions(disk, id, file, l);
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files.put(id, new Data(file, file + l - 1, l));
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}
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});
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}
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private int findFile(List<Integer> disk, int length, int start) {
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int count = 0, segmentStart = -1;
97+
for (int i = 0; i < start; i++) {
98+
if (disk.get(i) == -1) {
99+
if (segmentStart == -1) segmentStart = i;
100+
if (++count == length) return segmentStart;
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} else {
102+
count = 0;
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segmentStart = -1;
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}
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}
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return -1;
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}
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private void clearOldPositions(List<Integer> disk, Data data) {
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rangeClosed(data.start(), data.end()).forEach(pos -> disk.set(pos, -1));
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}
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private void setNewPositions(List<Integer> disk, int id, int start, int length) {
114+
range(start, start + length).forEach(pos -> disk.set(pos, id));
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}
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private long checksum(List<Integer> disk) {
118+
return zipWithIndex(disk.stream()).filter(b -> b.e() != -1).mapToLong(b -> (long) b.i() * b.e()).sum();
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}
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}

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