Hackerrank - Find Point - Pavol Pidanič

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

Solution
For solution you can check wikipedia page for Point reflection.

I created solution in:

Java
JavaScript
Scala
Ruby

All solutions are also available on my GitHub.

Java

import java.util.*;

public class FindPoint {

    public static void main(String[] args) {
        Scanner stdin = new Scanner(System.in);
        int points = stdin.nextInt();
        for(int i = 0; i < points; i++) {
            int x = stdin.nextInt();
            int y = stdin.nextInt();
            int mx = stdin.nextInt();
            int my = stdin.nextInt();
            int sx = 2 * mx - x;
            int sy = 2 * my - y;
            System.out.println(sx + " " + sy);
        }
        stdin.close();
    }
}

import java.util.*;

public class FindPoint {

public static void main(String[] args) {

Scanner stdin = new Scanner(System.in);

int points = stdin.nextInt();

for(int i = 0; i < points; i++) {

int x = stdin.nextInt();

int y = stdin.nextInt();

int mx = stdin.nextInt();

int my = stdin.nextInt();

int sx = 2 * mx - x;

int sy = 2 * my - y;

System.out.println(sx + " " + sy);

}

stdin.close();

}

JavaScript

function processData(input) {
    var lines = input.split("\n");
    //var points = parseInt(lines[0]);
    for(var i = 1; i < lines.length; i++) {
        var coordinates = lines[i].split(" ").map(i => parseInt(i));
        var x = coordinates[0];
        var y = coordinates[1];
        var mx = coordinates[2];
        var my = coordinates[3];
        var sx = 2 * mx - x;
        var sy = 2 * my - y;
        console.log(sx + " " + sy);
    }
}

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 points = parseInt(lines[0]);

for(var i = 1; i < lines.length; i++) {

var coordinates = lines[i].split(" ").map(i => parseInt(i));

var x = coordinates[0];

var y = coordinates[1];

var mx = coordinates[2];

var my = coordinates[3];

var sx = 2 * mx - x;

var sy = 2 * my - y;

console.log(sx + " " + sy);

}

process.stdin.resume();

process.stdin.setEncoding("ascii");

_input = "";

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

_input += input;

});

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

processData(_input);

});

Scala

import scala.io.Source

case class Point(val x: Int, val y: Int) {
  def reflection(midPoint: Point): Point = {
    val rx = 2 * midPoint.x - x
    val ry = 2 * midPoint.y - y
    Point(rx, ry)
  }
}

object FindPoint extends App {
  val coordinates = Source.stdin.getLines().drop(1)
  coordinates.foreach {
    lines => {
      val ints = lines.split(" ").map(_.toInt)
      val point = Point(ints(0), ints(1))
      val midPoint = Point(ints(2), ints(3))
      val symmetricPoint = point.reflection(midPoint)
      println(s"${symmetricPoint.x} ${symmetricPoint.y}")
    }
  }
}

import scala.io.Source

case class Point(val x: Int, val y: Int) {

def reflection(midPoint: Point): Point = {

val rx = 2 * midPoint.x - x

val ry = 2 * midPoint.y - y

Point(rx, ry)

}

object FindPoint extends App {

val coordinates = Source.stdin.getLines().drop(1)

coordinates.foreach {

lines => {

val ints = lines.split(" ").map(_.toInt)

val point = Point(ints(0), ints(1))

val midPoint = Point(ints(2), ints(3))

val symmetricPoint = point.reflection(midPoint)

println(s"${symmetricPoint.x} ${symmetricPoint.y}")

}

Ruby

class Point
  attr_reader :x, :y
  
  def initialize(x, y)
    @x = x
    @y = y
  end

  def self.symetric_point(point, midpoint)
    x = 2 * midpoint.x - point.x
    y = 2 * midpoint.y - point.y
    return Point.new(x, y)
  end
end


tests = gets.chomp.to_i
tests.times do
  coordinates = gets.chomp.split.map { |e| e.to_i }
  half1 = coordinates.slice(0..1)
  half2 = coordinates.slice(2..3)
  point = Point.new(half1[0], half1[1])
  midpoint = Point.new(half2[0], half2[1])
  
  symetric_point = Point.symetric_point(point, midpoint)
  puts "#{symetric_point.x} #{symetric_point.y}"
end

class Point

attr_reader :x, :y

def initialize(x, y)

@x = x

@y = y

end

def self.symetric_point(point, midpoint)

x = 2 * midpoint.x - point.x

y = 2 * midpoint.y - point.y

return Point.new(x, y)

end

tests = gets.chomp.to_i

tests.times do

coordinates = gets.chomp.split.map { |e| e.to_i }

half1 = coordinates.slice(0..1)

half2 = coordinates.slice(2..3)

point = Point.new(half1[0], half1[1])

midpoint = Point.new(half2[0], half2[1])

symetric_point = Point.symetric_point(point, midpoint)

puts "#{symetric_point.x} #{symetric_point.y}"

end

Pavol Pidanič

I can count to 1023 with 10 fingers

Hackerrank – Find Point