Day 11: HackerRank 30 Days Of Code Solution | 2D Arrays

This post explains the HackerRank 30 Days of Code problem 2D Arrays step by step: the problem statement, input and output format, constraints, a sample test case and a working solution in Java that you can study and run.

Day 11: 2D Arrays

Objective

So this problem is based on the concept of 2D arrays which is an important concept in java.Here we will come to know how 2D arrays can be used so lets see the problem codinghumans .

Here a 2D Array, is given of the order 6 x 6

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0

We define an hourglass in A to be a subset of values with indices falling in this pattern in A's graphical representation:

a b c
  d
e f g

There are 16 hourglasses in A, and an hourglass sum is the sum of an hourglass' values.

Task

Our task is to calculate the hourglass sum for every hourglass in , then print the maximum hourglass sum.

Input Format

There are 6 lines of input, where each line contains 6 space-separated integers describing 2D Array ; every value in A will be in the inclusive range of - 9 to 9.

Constraints

-9<=A[i][j]<=9
0<=i,j<=5

Output Format

we need to print the largest hourglass sum found in A .

Sample Input

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0
0 0 2 4 4 0
0 0 0 2 0 0
0 0 1 2 4 0

Sample Output

19

Explanation

A contains the following hourglasses:

1 1 1   1 1 0   1 0 0   0 0 0
  1           0       0       0
1 1 1   1 1 0   1 0 0   0 0 0

0 1 0   1 0 0   0 0 0   0 0 0
  1           1       0       0
0 0 2   0 2 4   2 4 4   4 4 0

1 1 1   1 1 0   1 0 0   0 0 0
  0          2       4       4
0 0 0   0 0 2   0 2 0   2 0 0

0 0 2   0 2 4   2 4 4   4 4 0
  0       0            2       0
0 0 1   0 1 2   1 2 4   2 4 0

The hourglass with the maximum sum (19) is:

2 4 4
  2
1 2 4

2D Arrays Solution in Java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int arr[][] = new int[6][6];
        for(int i=0; i < 6; i++){
            for(int j=0; j < 6; j++){
                arr[i][j] = in.nextInt();
            }
        }

        int sum[] = new int[16];
    int h = 0;
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            sum[h] = arr[i][j] + arr[i][j+1] + arr[i][j+2]
                    + arr[i+1][j+1] + arr[i+2][j] + arr[i+2][j+1]
                    + arr[i+2][j+2];
            h++;
        }
    }
    Arrays.sort(sum);
    System.out.println(sum[15]);
    }
}

If you need solutions in other programming languages or have any doubts regarding this problem then leave a comment down below .

Tip: try to solve the problem yourself before reading the solution. Use the code as a reference to check your approach, and make sure you understand why it works.

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