Day 1: Quartiles HackerRank Solution

Day 1: Quartiles HackerRank Solution
Source : https://www.hackerrank.com/challenges/s10-quartiles

Objective
In this challenge, we practice calculating quartiles. Check out the Tutorial tab for learning materials and an instructional video!

Task
Given an array, , of integers, calculate the respective first quartile (), second quartile (), and third quartile (). It is guaranteed that , , and are integers.

Input Format

The first line contains an integer, , denoting the number of elements in the array.
The second line contains space-separated integers describing the array's elements.

Constraints

• , where is the element of the array.

Output Format

Print lines of output in the following order:

1. The first line should be the value of .
2. The second line should be the value of .
3. The third line should be the value of .

Sample Input

93 7 8 5 12 14 21 13 18

Sample Output

61216

Explanation

. When we sort the elements in non-decreasing order, we get . It's easy to see that .

As there are an odd number of data points, we do not include the median (the central value in the ordered list) in either half:

Lower half (L): 3, 5, 7, 8

Upper half (U): 13, 14, 18, 21

Now, we find the quartiles:

• is the . So, .
• is the . So, .
• is the . So, .

Source : https://www.hackerrank.com/challenges/s10-quartiles

Solution

	// github.com/RodneyShag
	import java.util.Scanner;
	import java.util.Arrays;
	public class Solution {
	public static void main(String[] args) {
	int [] array = getValues();
	Arrays.sort(array);
	int q1 = findMedian(array, 0, array.length / 2 - 1);
	int q2 = findMedian(array, 0, array.length - 1);
	int q3 = findMedian(array, (array.length + 1) / 2, array.length - 1);
	System.out.println(q1);
	System.out.println(q2);
	System.out.println(q3);
	}
	/* Creates array from input */
	private static int [] getValues() {
	Scanner scan = new Scanner(System.in);
	int n = scan.nextInt();
	int [] array = new int[n];
	for (int i = 0; i < n; i++) {
	array[i] = scan.nextInt();
	}
	scan.close();
	return array;
	}
	/* Treats elements from "start" to "end" (inclusive) as an array and calculates its median */
	private static int findMedian(int [] array, int start, int end) {
	if ((end - start) % 2 == 0) { // odd number of elements
	return (array[(end + start) / 2]);
	} else { // even number of elements
	int value1 = array[(end + start) / 2];
	int value2 = array[(end + start) / 2 + 1];
	return Math.round((value1 + value2) / 2);
	}
	}
	}