Question

Rewrite this code in Java please

#include <iostream>

#include <fstream>

#include <cstdlib>

#include <ctime>

using namespace std;

long length = 1000;

const long max_length = 100000;

int list[max_length];

void read()

{

    ifstream fin("random.dat", ios::binary);

    for (long i = 0; i < length; i++)

    {

        fin.read((char*)&list[i], sizeof(int));

    }

    fin.close();

}

void bubbleSort()

{

    int temp;

    for(long i = 0; i < length; i++)

    {

        for(long j = 0; j< length-i-1; j++)

        {

            if (list[j] > list[j+1])

            {

                temp        = list[j];

                list[j]     = list[j+1];

                list[j+1] = temp;

            }

        }

    }

}

void insertionSort()

{

    int temp;

    for(long i = 1; i < length; i++)

    {

        temp = list[i];

        long j;

        for(j = i-1; j >= 0 && list[j] > temp; j--)

        {

            list[j+1] = list[j];

        }

        list[j+1] = temp;

    }

}

long partition(long left, long right)

{

    int pivot_element = list[left];

    int lb = left, ub = right;

    int temp;

    while (left < right)

    {

        while(list[left]< = pivot_element)

            left++;

        while(list[right]> pivot_element)

            right--;

        if (left < right)

        {

            temp        = list[left];

            list[left] = list[right];

            list[right] = temp;

        }

    }

    list[lb] = list[right];

    list[right] = pivot_element;

    return right;

}

void quickSort(long left, long right)

{

    if (left < right)

    {

        long pivot = partition(left, right);

        quickSort(left, pivot-1);

        quickSort(pivot+1, right);

    }

}

int main()

{

    double t1, t2;

    for (length = 1000; length <= max_length; )

    {

        cout << "\nLength\t: " << length << '\n';

        read();

        t1 = clock();

        bubbleSort();

        t2 = clock();

        cout << "Bubble Sort\t: " << (t2 - t1)/CLK_TCK << " sec\n";

        read();

        t1 = clock();

        insertionSort();

        t2 = clock();

        cout << "Insertion Sort\t: " << (t2 - t1)/CLK_TCK << " sec\n";

        read();

        t1 = clock();

        quickSort(0, length - 1);

        t2 = clock();

        cout << "Quick Sort\t: " << (t2 - t1)/CLK_TCK << " sec\n";

        switch (length)

        {

        case 1000 :

            length = 5000;

            break;

        case 5000 :

            length = 10000;

            break;

        case 10000 :

            length = 20000;

            break;

        case 20000 :

            length = 50000;

            break;

        case 50000 :

            length = 100000;

            break;

      case 100000 :

            length = 100001;

            break;

        }

    }

    return 0;

}

Answer 1

Here is the coverted Java version for you:

import java.util.*;
class SortingTime
{
static int length = 1000;
final static int max_length = 100000;
static int list[] = new int[max_length];
public static void read()
{
Scanner in = new Scanner(System.in);
in = new Scanner("random.dat");
for (int i = 0; i < length; i++)
{
list[i] = in.nextInt();
}
}
public static void bubbleSort()
{
int temp;
for(int i = 0; i < length; i++)
{
for(int j = 0; j< length-i-1; j++)
{
if (list[j] > list[j+1])
{
temp = list[j];
list[j] = list[j+1];
list[j+1] = temp;
}
}
}
}
public static void insertionSort()
{
int temp;
for(int i = 1; i < length; i++)
{
temp = list[i];
int j;
for(j = i-1; j >= 0 && list[j] > temp; j--)
{
list[j+1] = list[j];
}
list[j+1] = temp;
}
}
public static int partition(int left, int right)
{
int pivot_element = list[left];
int lb = left, ub = right;
int temp;
while (left < right)
{
while(list[left] <= pivot_element)
left++;
while(list[right]> pivot_element)
right--;
if (left < right)
{
temp = list[left];
list[left] = list[right];
list[right] = temp;
}
}
list[lb] = list[right];
list[right] = pivot_element;
return right;
}
public static void quickSort(int left, int right)
{
if (left < right)
{
int pivot = partition(left, right);
quickSort(left, pivot-1);
quickSort(pivot+1, right);
}
}
public static void main(String[] args)
{
double t1, t2;
for (length = 1000; length <= max_length; )
{
System.out.println("\nLength\t: " + length);
read();
t1 = System.currentTimeMillis();;
bubbleSort();
t2 = System.currentTimeMillis();;
System.out.println("Bubble Sort\t: " + (t2 - t1) + " sec");
read();
t1 = System.currentTimeMillis();;
insertionSort();
t2 = System.currentTimeMillis();;
System.out.println( "Insertion Sort\t: " + (t2 - t1) + " sec");
read();
t1 = System.currentTimeMillis();
quickSort(0, length - 1);
t2 = System.currentTimeMillis();
System.out.println( "Quick Sort\t: " + (t2 - t1) + " sec");
switch (length)
{
case 1000 :
length = 5000;
break;
case 5000 :
length = 10000;
break;
case 10000 :
length = 20000;
break;
case 20000 :
length = 50000;
break;
case 50000 :
length = 100000;
break;
case 100000 :
length = 100001;
break;
}
}
}
}