Hackerrank - Diagonal Difference

Problem Statement
A description of the problem can be found on Hackerrank.

Solution
Make 2 sums for 2 diagonals – from left to right, from right to left.
Substract 2 sums and print its absolute value.

I created solution in 4 languages:

Scala
Java
JavaScript
Ruby

All solutions are also available on my GitHub.

Scala

object DiagonalDifference extends App {
  val lines = io.Source.stdin.getLines().toList
  val n = lines.head.toInt
  val matrix = lines.tail.toArray.map(_.split(" ").map(_.toInt))

  var leftRight = 0
  var rightLeft = 0
  (0 until n).foreach {
    i =>
      leftRight += (matrix(i))(i)
      rightLeft += (matrix(i)(n - i - 1))
  }
  println((leftRight - rightLeft).abs)
}

object DiagonalDifference extends App {

val lines = io.Source.stdin.getLines().toList

val n = lines.head.toInt

val matrix = lines.tail.toArray.map(_.split(" ").map(_.toInt))

var leftRight = 0

var rightLeft = 0

(0 until n).foreach {

i =>

leftRight += (matrix(i))(i)

rightLeft += (matrix(i)(n - i - 1))

}

println((leftRight - rightLeft).abs)

}

Java

import java.util.Scanner;

public class DiagonalDifference 
{
	public static void main(String[] args)
	{
		Scanner stdin = new Scanner(System.in);
		int n = Integer.parseInt(stdin.nextLine());
		long sumLeftRight = 0;
		long sumRightLeft = 0;
		for(int i = 0; i < n; i++)
		{
			String[] elements = stdin.nextLine().split(" ");
			sumLeftRight += Long.parseLong(elements[i]);
			sumRightLeft += Long.parseLong(elements[n - i - 1]);
		}
		System.out.println(Math.abs(sumLeftRight - sumRightLeft));
		stdin.close();
	}
}

import java.util.Scanner;

public class DiagonalDifference

{

public static void main(String[] args)

{

Scanner stdin = new Scanner(System.in);

int n = Integer.parseInt(stdin.nextLine());

long sumLeftRight = 0;

long sumRightLeft = 0;

for(int i = 0; i < n; i++)

{

String[] elements = stdin.nextLine().split(" ");

sumLeftRight += Long.parseLong(elements[i]);

sumRightLeft += Long.parseLong(elements[n - i - 1]);

}

System.out.println(Math.abs(sumLeftRight - sumRightLeft));

stdin.close();

}

JavaScript

function processData(input) {
    var lines = input.split('\n');
    var n = parseInt(lines[0]);
    var sumLeftRight = 0;
    var sumRightLeft = 0;
    for(var i = 0; i < n; i++)
    {
        var elements = lines[i + 1].split(" ").map(function(s) {return parseInt(s)});
        sumLeftRight += elements[i];
        sumRightLeft += elements[n - i - 1];
    }
    console.log(Math.abs(sumLeftRight - sumRightLeft));
}

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
    processData(_input);
});

function processData(input) {

var lines = input.split('\n');

var n = parseInt(lines[0]);

var sumLeftRight = 0;

var sumRightLeft = 0;

for(var i = 0; i < n; i++)

{

var elements = lines[i + 1].split(" ").map(function(s) {return parseInt(s)});

sumLeftRight += elements[i];

sumRightLeft += elements[n - i - 1];

}

console.log(Math.abs(sumLeftRight - sumRightLeft));

}

process.stdin.resume();

process.stdin.setEncoding("ascii");

_input = "";

process.stdin.on("data", function (input) {

_input += input;

});

process.stdin.on("end", function () {

processData(_input);

});

Ruby

n = gets.to_i
leftRight = 0
rightLeft = 0
n.times do |i|
  row = gets.to_s.split(" ").map { |s| s.to_i}
  leftRight += row[i]
  rightLeft += row[n - i - 1]
end

puts (leftRight - rightLeft).abs

n = gets.to_i

leftRight = 0

rightLeft = 0

n.times do |i|

row = gets.to_s.split(" ").map { |s| s.to_i}

leftRight += row[i]

rightLeft += row[n - i - 1]

end

puts (leftRight - rightLeft).abs

Pavol Pidanič

I can count to 1023 with 10 fingers

Hackerrank – Diagonal Difference