Day 3 implementation in Java

java/src/main/java/day3/Main.java

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+package day3;
+
+import io.vavr.Tuple;
+import io.vavr.Tuple2;
+import io.vavr.collection.List;
+import io.vavr.collection.Set;
+import util.FileReader;
+
+public class Main {
+
+    public static void main(String[] args) {
+        String inputFilePath = System.getProperty("user.dir") + "\\java\\src\\main\\java\\day3\\input.txt";
+        FileReader reader = new FileReader(inputFilePath);
+        List<String> inputData = List.ofAll(reader.readContents());
+
+        Set<Position> symbolsPositions = inputData
+            .zipWithIndex()
+            .toMap(Tuple2::swap)
+            .mapValues(String::toCharArray)
+            .mapValues(List::ofAll)
+            .mapValues(charArray -> charArray
+                .zipWithIndex()
+                .toMap(Tuple2::swap)
+                .filterValues(character -> '.' != character)
+                .filterValues(character -> !Character.isDigit(character))
+                .keySet().toList()
+            ).map((lineIndex, columnIndexes) -> Tuple.of(lineIndex, columnIndexes
+                    .map(columnIndex -> new Position(lineIndex, columnIndex))
+                )
+            ).values().toSet()
+            .flatMap(set -> set);
+
+        List<List<Position>> numbersPositions = inputData
+            .zipWithIndex()
+            .toMap(Tuple2::swap)
+            .mapValues(String::toCharArray)
+            .mapValues(List::ofAll)
+            .mapValues(charArray -> charArray
+                .zipWithIndex()
+                .toMap(Tuple2::swap)
+                .filterValues(Character::isDigit)
+                .keySet().toList()
+            )
+            .mapValues(Main::groupConsecutiveNumbers)
+            .map((lineIndex, groupedNumbersColumnIndexes) -> Tuple.of(lineIndex, groupedNumbersColumnIndexes
+                    .map(columnIndexes -> columnIndexes.map(columnIndex -> new Position(lineIndex, columnIndex)))
+                )
+            ).values().toList().flatMap(list -> list);
+
+        Integer sumOfValidParts = numbersPositions.filter(positions ->
+            !positions.filter(numberPosition ->
+                !symbolsPositions
+                    .filter(symbolPosition -> symbolPosition.isAdjacent(numberPosition))
+                    .isEmpty()
+            ).isEmpty()
+        ).map(positions -> transformDigitsPositionsToNumber(positions, inputData))
+        .reduce(Integer::sum);
+
+        System.out.println(sumOfValidParts);
+
+        Integer gearRatiosSum = symbolsPositions.toList()
+            .filter(position -> inputData.get(position.line).charAt(position.column) == '*')
+            .map(symbolPosition -> numbersPositions
+                .filter(numberPositions -> !numberPositions.filter(symbolPosition::isAdjacent).isEmpty())
+            ).filter(adjacentNumberList -> adjacentNumberList.length() == 2)
+            .map(adjacentNumberPositions -> adjacentNumberPositions.map(positions -> transformDigitsPositionsToNumber(positions, inputData)))
+            .map(adjacentNumbers -> adjacentNumbers.get(0) * adjacentNumbers.get(1))
+            .reduce(Integer::sum);
+
+        System.out.println(gearRatiosSum);
+    }
+
+    private static Integer transformDigitsPositionsToNumber(List<Position> digitsPositions, List<String> inputData) {
+        return digitsPositions
+            .map(position -> inputData
+                .get(position.line)
+                .charAt(position.column)
+            ).map(String::valueOf)
+            .map(Integer::parseInt)
+            .reduce((accumulator, value) -> 10 * accumulator + value);
+    }
+
+    private static List<List<Integer>> groupConsecutiveNumbers(List<Integer> numbers) {
+        List<Integer> sortedNumbers = numbers.sorted();
+        List<List<Integer>> groupedNumbers = List.empty();
+
+        List<Integer> temp = List.empty();
+        temp = temp.append(sortedNumbers.get(0));
+
+        for (int index = 0; index < sortedNumbers.size() - 1; index++) {
+            if (sortedNumbers.get(index + 1) != sortedNumbers.get(index) + 1) {
+                groupedNumbers = groupedNumbers.append(temp);
+                temp = List.empty();
+            }
+            temp = temp.append(sortedNumbers.get(index + 1));
+        }
+
+        return groupedNumbers.append(temp);
+    }
+}

java/src/main/java/day3/Position.java

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+package day3;
+
+import lombok.AllArgsConstructor;
+
+@AllArgsConstructor
+public class Position {
+    Integer line;
+    Integer column;
+
+    public boolean isAdjacent(Position other) {
+        int columnsDiff = Math.abs(this.column - other.column);
+        int linesDiff = Math.abs(this.line - other.line);
+        return columnsDiff <= 1 && linesDiff <= 1;
+    }
+}