Day 7 implementation in Java

java/src/main/java/day7/Hand.java

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+package day7;
+
+import io.vavr.collection.HashMap;
+import io.vavr.collection.List;
+import io.vavr.collection.Map;
+import lombok.Getter;
+
+import static day7.HandType.getHandType;
+
+@Getter
+public class Hand implements Comparable<Hand> {
+    private static final boolean ARE_JOKERS_ENABLED = true;
+    private static final Integer JOKERS_VALUE = ARE_JOKERS_ENABLED ? 1 : 11;
+
+    private static final Map<Character, Integer> CARD_SYMBOLS_TO_VALUES = HashMap.of(
+        'T', 10,
+        'J', JOKERS_VALUE,
+        'Q', 12,
+        'K', 13,
+        'A', 14
+    );
+
+    private final List<Integer> cards;
+    private final HandType type;
+
+    public Hand(String handRepresentation) {
+        this.cards = List.ofAll(handRepresentation.toCharArray())
+            .map(cardSymbol -> CARD_SYMBOLS_TO_VALUES
+                .get(cardSymbol)
+                .getOrElse(() -> Integer.parseInt(String.valueOf(cardSymbol))));
+        this.type = getHandType(cards);
+    }
+
+    @Override
+    public int compareTo(Hand other) {
+        if (!this.getType().getValue().equals(other.getType().getValue())) {
+            return this.type.getValue() - other.type.getValue();
+        }
+
+        return this.cards
+            .zip(other.getCards())
+            .map(cardsPair -> cardsPair._1 - cardsPair._2)
+            .find(cardsDifference -> cardsDifference != 0)
+            .getOrElse(0);
+    }
+}

java/src/main/java/day7/HandType.java

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+package day7;
+
+import io.vavr.Tuple2;
+import io.vavr.collection.List;
+import io.vavr.collection.Map;
+import lombok.Getter;
+
+import java.util.Collections;
+
+@Getter
+public enum HandType {
+    RE_POKER(6),
+    POKER(5),
+    FULL_HOUSE(4),
+    THREE(3),
+    DOUBLE_PAIR(2),
+    PAIR(1),
+    NOTHING(0);
+
+    private final Integer value;
+    HandType(Integer value) {
+        this.value = value;
+    }
+
+    public static HandType getHandType(List<Integer> cards) {
+        Map<Integer, Integer> groupedCards = cards.toMap(
+            card -> card,
+            card -> Collections.frequency(cards.toJavaList(), card)
+        );
+
+        Integer jokersCount = groupedCards.get(1).getOrElse(0);
+
+        java.util.List<Integer> sortedCardCounts = groupedCards
+            .filterKeys(card -> card != 1)
+            .map(Tuple2::_2)
+            .sorted()
+            .toJavaList();
+
+        if (sortedCardCounts.size() != 0) {
+            sortedCardCounts.add(
+                sortedCardCounts.remove(sortedCardCounts.size() - 1) + jokersCount
+            );
+        } else {
+            sortedCardCounts.add(groupedCards.get(1).getOrElseThrow(RuntimeException::new));
+        }
+
+        return determineHandTypeBasedOnCardCounts(List.ofAll(sortedCardCounts));
+    }
+
+    private static HandType determineHandTypeBasedOnCardCounts(List<Integer> cardCounts) {
+        if (cardCounts.contains(5)) {
+            return RE_POKER;
+        }
+        if (cardCounts.contains(4)) {
+            return POKER;
+        }
+        if (cardCounts.contains(3) && cardCounts.contains(2)) {
+            return FULL_HOUSE;
+        }
+        if (cardCounts.contains(3)) {
+            return THREE;
+        }
+        if (cardCounts.contains(2) && cardCounts.length() == 3) {
+            return DOUBLE_PAIR;
+        }
+        if (cardCounts.contains(2)) {
+            return PAIR;
+        }
+        return NOTHING;
+    }
+}

java/src/main/java/day7/Main.java

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+package day7;
+
+import io.vavr.Tuple2;
+import io.vavr.collection.List;
+import util.FileReader;
+
+public class Main {
+
+    public static void main(String[] args) {
+        String inputFilePath = System.getProperty("user.dir") + "\\java\\src\\main\\java\\day7\\input.txt";
+        FileReader reader = new FileReader(inputFilePath);
+        List<String> inputData = List.ofAll(reader.readContents());
+
+        List<Tuple2<Hand, Integer>> handsAndBids = inputData
+            .map(string -> string.split(" "))
+            .map(List::of)
+            .map(splitInputLine -> new Tuple2<>(
+                new Hand(splitInputLine.get(0)),
+                Integer.parseInt(splitInputLine.get(1))
+            ));
+
+        Integer result = handsAndBids
+            .sorted()
+            .map(Tuple2::_2)
+            .zipWithIndex()
+            .map(bidAndValue -> bidAndValue._1 * ( bidAndValue._2 + 1 ))
+            .reduce(Integer::sum);
+
+        System.out.println(result);
+    }
+}