Solution.java

package hackrank.algorithm.greedy.priyanka;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

/**
 * Priyanka and Toys Challenge
 *
 * @see https://www.hackerrank.com/challenges/priyanka-and-toys
 */
public class Solution {

    public static void main(String[] args) {

        List<Integer> weights = readInput(System.in);
        System.out.println(calcMinUnits(weights));
    }

    public static int calcMinUnits(List<Integer> weights) {

        Collections.sort(weights);

        int units = 0;
        int freeRange = -1;

        for (int weight : weights) {
            if (weight > freeRange) {
                units++;
                freeRange = weight + 4;
            }
        }

        return units;
    }

    public static List<Integer> readInput(InputStream stream) {

        Scanner scanner = new Scanner(stream);

        int size = scanner.nextInt();
        List<Integer> weights = new ArrayList<>(size);
        for (int i = 0; i < size; i++) {
            weights.add(scanner.nextInt());
        }

        scanner.close();

        return weights;
    }

}