package Algorithms.lessons;

import java.util.Arrays;
import java.util.Scanner;

public class MergeSort
{
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		int N, start, end;
		do
		{
			start = scanner.nextInt();
			end = scanner.nextInt();
			N = scanner.nextInt();
		} while (N <= 0 && start < 0 && end > start && N < end);
		double[] arr = new double[N];
		for(int i = 0; i < N; i++)
		{
			arr[i] = Math.random();
		}
		mergeSort(arr, start, end);
		for(int i = 0; i < N; i++)
		{
			System.out.printf("arr[%d] = %f\n", i, arr[i]);
		}
	}
	
	public static void mergeSort(double[] arr, int start, int end)
	{
		int q;
		if(start >= end)  // подмассив arr содержит не более одного элемента
		{
			return;
		}
		else
		{
			q = (int)((start + end)/2);
			mergeSort(arr, start, q);
			mergeSort(arr, q + 1, end);
			merge(arr, start, q, end);
		}	
	}
	
	public static double[] merge(double[] arr, int start, int q, int end)
	{
		int n1 = q - start + 1;
		int n2 = end - q;
		double[] B = new double[n1 + 1];
		double[] C = new double[n2 + 1];
		B = Arrays.copyOfRange(arr, start, q + 1);
		C = Arrays.copyOfRange(arr, q + 1, end + 1);
		B[n1] = C[n2] = Double.MAX_VALUE;
		int i = 0;
		int j = 0;
		for(int k = start; k < q; k++)
		{
			if(B[i] <= C[j])
			{
				arr[k] = B[i];
				i++;
			}
			else
			{
				arr[k] = C[j];
				j++;
			}
		}
		return arr;
	}
}

0
10
11
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
	at Algorithms.lessons.MergeSort.merge(MergeSort.java:54)
	at Algorithms.lessons.MergeSort.mergeSort(MergeSort.java:42)
	at Algorithms.lessons.MergeSort.mergeSort(MergeSort.java:40)
	at Algorithms.lessons.MergeSort.mergeSort(MergeSort.java:40)
	at Algorithms.lessons.MergeSort.mergeSort(MergeSort.java:40)
	at Algorithms.lessons.MergeSort.main(MergeSort.java:23)