ListSolution2.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

    public static int hourglassSum(List<List<Integer>> arr) {

        int hourGlassSum = 0;
        int maxHourGlassSum = Integer.MIN_VALUE;

        for(int i = 0; i < 4; i++){      
            for(int j = 0; j < 4; j++){
                
                hourGlassSum = calculateHourGlass(arr, i, j);

                if(hourGlassSum > maxHourGlassSum){
                    maxHourGlassSum = hourGlassSum;
                }
            }
        }
                
        return maxHourGlassSum;
    }
    
    private static int calculateHourGlass(List<List<Integer>> arr, int i, int j) {
        int sum = arr.get(i).get(j) + arr.get(i).get(j + 1) + arr.get(i).get(j + 2) + arr.get(i + 1).get(j + 1) + arr.get(i + 2).get(j) + arr.get(i + 2).get(j + 1) + arr.get(i + 2).get(j + 2);
        
        return sum;
    }

}

public class ListSolution2 {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        List<List<Integer>> arr = new ArrayList<>();

        IntStream.range(0, 6).forEach(i -> {
            try {
                arr.add(
                    Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
                        .map(Integer::parseInt)
                        .collect(toList())
                );
            } catch (IOException ex) {
                throw new RuntimeException(ex);
            }
        });

        int result = Result.hourglassSum(arr);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedReader.close();
        bufferedWriter.close();
    }
}