Algorithm


Problem Name: 30 days of code - Day 11: 2D Arrays

Problem Link: https://www.hackerrank.com/challenges/30-2d-arrays/problem?isFullScreen=true

In this HackerRank in 30 Days of Code ay 11: 2D Arrays problem solution,

Objective
Today, we are building on our knowledge of arrays by adding another dimension. Check out the Tutorial tab for learning materials and an instructional video.

Context
Given a 6 * 6 2D Array, A:

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
Calculate the hourglass sum for every hourglass in A, then print the maximum hourglass sum.

Example

In the array shown above, the maximum hourglass sum is 7 for the hourglass in the top left corner.

Input Format

There are 6 lines of input, where each line contains 6 space-separated integers that describe the 2D Array A.

Constraints

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

Output Format

Print the maximum hourglass sum 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

 

 

 

 

 

 

 

Code Examples

#1 Code Example with C Programming

Code - C Programming


#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(){
    int arr[6][6];
    for(int i = 0; i  <  6; i++){
        for(int j = 0; j  <  6; j++){
            scanf("%d", &arr[i][j]);
        }
    }
    int max_sum = 0;
    int temp_sum;
    for(int i = 0; i  <  4; i++) {
        for(int j = 0; j  <  4; j++) {
            temp_sum = 0;
            // top row
            temp_sum += arr[i][j];
            temp_sum += arr[i][j + 1];
            temp_sum += arr[i][j + 2];
            //middle 
            temp_sum += arr[i+1][j+1];
            //bottom row
            temp_sum += arr[i + 2][j];
            temp_sum += arr[i + 2][j + 1];
            temp_sum += arr[i + 2][j + 2];
            
            //if first hourglass, set as max
            if(temp_sum > max_sum || i == 0 && j == 0)
                max_sum = temp_sum;
        }
    }
    printf("%d\n", max_sum);
    return 0;
}
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#2 Code Example with C++ Programming

Code - C++ Programming


#include <iostream>
#include <vector>

using namespace std;

int main() {
    vector < vector<int>> arr(6, vector<int>(6));
    for (int i = 0; i  <  6; i++) {
        for (int j = 0; j  <  6; j++) {
            cin >> arr[i][j];
        }
    }

    int max = -9 * 7;
    for (int i = 0; i  <  6; i++) {
        for (int j = 0; j  <  6; j++) {
            if (j + 2 < 6 && i + 2 < 6) {
                int sum = 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];
                if (sum > max) max = sum;
            }
        }
    }

    cout << max;

    return 0;
}
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#3 Code Example with C# Programming

Code - C# Programming


using System;

class Solution
{
    static void Main(String[] args)
    {
        int[][] arr = new int[6][];
        for (int i = 0; i  <  6; i++)
        {
            var tmp = Console.ReadLine().Split(' ');
            arr[i] = Array.ConvertAll(tmp, int.Parse);
        }

        int max = -9 * 7;
        for (int i = 0; i  <  6; i++)
        {
            for (int j = 0; j  <  6; j++)
            {
                if (j + 2 < 6 && i + 2 < 6)
                {
                    int sum = 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];
                    if (sum > max) max = sum;
                }
            }
        }

        Console.WriteLine(max);
    }
}
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#4 Code Example with Golang Programming

Code - Golang Programming


package main

import "fmt"

func main() {
	var a [6][6]int
	var max int
	for i := range a {
		for j := range a[i] {
			fmt.Scan(&a[i][j])
		}
	}

	for i := 0; i  <  4; i++ {
		for j := 0; j  <  4; j++ {
			sumHourGlass := a[i][j] + a[i][j + 1] + a[i][j + 2] + a[i + 1][j + 1] + a[i + 2][j] + a[i + 2][j +1] + a[i + 2][j + 2]
			if (i == 0 && j == 0) || sumHourGlass > max {
				max = sumHourGlass
			}
		}
	}
	fmt.Println(max)
}
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#5 Code Example with Java Programming

Code - Java Programming


import java.util.Scanner;

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 max = -9 * 7;
        for (int i = 0; i  <  6; i++) {
            for (int j = 0; j  <  6; j++) {
                if (j + 2 < 6 && i + 2 < 6) {
                    int sum = 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];
                    if (sum > max) max = sum;
                }
            }
        }

        System.out.println(max);
    }
}
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#6 Code Example with Javascript Programming

Code - Javascript Programming


process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    var arr = [];
    for(arr_i = 0; arr_i  <  6; arr_i++){
       arr[arr_i] = readLine().split(' ');
       arr[arr_i] = arr[arr_i].map(Number);
    }
    
    var sumarr = [];
    
    var h = 0;
    for (var i = 0; i  <  4; i++) {
        for (var j = 0; j  <  4; j++) {
            sumarr[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++;
        }
    }

    sumarr.sort();
    
    var max = -99999;
    for (var x = 0; x  <  16; x++){
        if (sumarr[x] > max)
            max = sumarr[x];
    }
    
    console.log(max);
}
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#7 Code Example with Python Programming

Code - Python Programming


arr = []

for _ in range(6):
    tmp = [int(x) for x in str(input()).split(" ")]
    arr.append(tmp)

maximum = -9 * 7

for i in range(6):
    for j in range(6):
        if j + 2 < 6 and i + 2 < 6:
            result = 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]
            if result > maximum:
                maximum = result

print(maximum)
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Demonstration


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