Quicksort Implementation With Median Pivot

May 19, 2014

I am currently writing the Quick Sort implementation where the pivot is chosen to be the medianOf3 element in the sub array. The program should output the total number of comparisons (excluding the ones needed to compute the median itself).I cannot spot any mistake anywhere - yet I am getting the wrong output in the end.

Input file (100.txt) attached.
Current output: 513. Correct output: 518. Where are the missing 5 comparisons? />

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;

[code]....

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Pseudocode For Quicksort Algorithm

May 6, 2015

I have been given this Pseudocode for the Quicksort algorithm:

quicksort(a[], p, r)
if r>p then
j=partition(a[], p, r)
quicksort(a[], p, j-1)
quicksort(a[], j+1, r)

[code]....

I was wondering why:

- why the condition left < right needs to be true for the while loop in the function Partition
- what the while loop does in the function Partition

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How To Get Median / Middle Value In Array

Apr 5, 2014

So first of all we use textpad in our java course (idk why) and the Easy.In method for our input. Any way I have this assignment and we're ask to make a program that input

1) how many numbers were input
2) the largest value
3)smallest value
4) average value and
5) middle/median value.

I manage to figure out the code for the other except the median value. Here's my code

class project2
{
public static void main(String[] args) {
System.out.println("How many numbers you want to input");
int maxItems = EasyIn.getInt();

[Code].....

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Finding Median Of Array?

May 3, 2014

I'm trying to find the median of a set of numbers inputted into an array and I wanted to know how I would pass the array to the median calculator after I use selection sort to organize the numbers.THIS IS THE CODE THAT ORGANIZES THE ARRAY:

public void selectionSort(double[] myArray) {
for (int i = 0; i < myArray.length - 1; i++)
{
int index = i;
for (int j = i + 1; j < myArray.length; j++)

if (myArray[j] < myArray[index])

[code]....

The code that finds the median will only work if the array being used is already organized. How do I pass the new sorted array to the code that finds the median?

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Characters From String In Alphabetic Order Using Quicksort

Oct 1, 2014

I am trying to do a program that takes all of the chars from a string and orders them in alphabetical order. It works fine, but when a is a last letter of a string it isn't being sorted.

Example: bcba = bbca, omnibus = bimnous (here u is in wrong place)

Here is my code:

public class sorty{
public static void sort(char[] a, int low, int high){
int i = low;
int j = high;
if (j - i < 2) return;
int m = (j+i)/2;
char p = a[m];

[Code] .....

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Determining Average Number Of Comparisons For Quicksort?

Feb 24, 2014

My objective is to execute quick sort ( i was told to convert the pseudocode from the Cormen book) using arrays of increasing sizes and find the average number of comparisons for each of those sizes over 100 iterations. This is a school project and the numbers I am getting are far larger than those of my friends, so I am clearly doing something wrong. I believe it must be in the way that I am collecting and averaging my number of comparisons. I will first give the method in which most of that calculating is done, then I will include the whole program.

public static void tests(int arraySize) {
long numComparisons = 0;
long averageComparisons = 0;
long[] numComparisonsArray = new long[100];
  for(int i = 0; i<100; i++) {
int[] array= genRandomArray(arraySize);

[code]....

I was simply not zeroing out one of my variables

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Java QuickSort Stack Overflow Error

Jan 19, 2014

I have an error using quicksort and this is a project ... The error occurs for numbers such as 7500 and bigger ...

Exception in thread "main" java.lang.StackOverflowError
at QuickSort.QuickSort(QuickSort.java:45)
at QuickSort.QuickSort(QuickSort.java:46)
at QuickSort.QuickSort(QuickSort.java:46) ...

Java Code:

import javax.swing.JOptionPane;
public class QuickSort{
public static void main(String[] args){
int p=new Integer(JOptionPane.showInputDialog("Jepni numrin e kufizave: "));
int[] ListaNumrave= new int[p];
//QuickSort Zbrites

[Code] .....

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Swing/AWT/SWT :: Implement The Median Filter?

Jun 10, 2014

I have to implement the median filter. I found an example on the internet but it does not run, I do not see the image

public void median_RGB(Immagine img) {
int maskSize = 3;
int width = img.getW();

[Code]....

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Quicksort With Single Linked List / 1 Node Parameter

Nov 12, 2014

I have a custom linkedList(single) class that uses the provided node class. Now I have another class to QuickSort this.(left out for brevity, i just wanna focus on editing the L.head). However, instead of passing the quicksort method the entire linkedList, I want to pass it just the head from the linkedlist.

My problem is accessing this head node and changing it from the quckSort method/class, and I dont want to delete it or simply just change the element value

Main:

public class TestLinkedList {
public static <E extends Comparable<E>> void main(String[] args) {
MyLinkedList<Integer> L = new MyLinkedList<Integer>();
L.add(3);
L.add(1);
L.add(2);
System.out.println("Initial=" + L);
MySort.quickSort(L.head);
System.out.println("After ="+L);
}
}

QuickSort:

public class MySort {
public static <E extends Comparable<E>> void quickSort(MyNode<E> list) {
list = list.next;
}

Node Class:

public class MyNode<E extends Comparable<E>> {
E element;
MyNode<E> next;
public MyNode(E item) {
element = item;
next = null;

[code]....

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Code That Find Median Value In List Of Values

Mar 19, 2014

a simple Java program for finding the median value in a list of values with the following requirements:

- Create an array with an even number of values in it (an odd number of values is little bit trickier, so if you want a challenge, do it for either an even or odd number of values)

- Find the value with an equal number of values greater than the value as there are values less than the value

- Your solution must not require a sorted list of values - Output the median value

This assignment is intended to get you to demonstrate basic knowledge of arrays, and to create methods with both input and output.

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Sort Values In Array And Print Median Value On Console

Oct 22, 2014

Use the sort method of the arrays class to sort the values in the array, and print the median value(the 50th value) on the console followed by a blank line. Then, test this enhancement. Print the 9th value of the array on the console and every 9th value after that. Then, test this enhancement.

import java.util.Arrays;
public class ArrayTestApp
{
public static void main(String[] args) {
double [] arrayTest = new double[99];
//adding random number to each element in the array
for(int i=0; i<arrayTest.length; i++)
arrayTest[i] = 100.0*Math.random();

[Code] ....

OUTPUT

run:

The average is: 49.842845462514944
The median is: 49.68753724038633
The 9th value is: 2.599530043466969
The 9th value is: 11.486193141397095
The 9th value is: 20.14206270200648

[Code] ....

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Finding And Printing Median Node In Linked List Using Recursion

Nov 3, 2014

The only problem I have now is getting a method to return the median element of a LinkedList without using loops of any kind or by using a global counter anywhere.

I've pretty easily figured out how to get the index value for the median number (there is some lee way allowed. If the list has an even size, any of the middle values are accepted) but I can't figure out how to print it without loops.

I'm sure I need to make a method that finds an element at the given index value, but I don't know how to do it without loops.

Here's all of my code. Inside is my Assignment3 class I use for testing, StudentList which contains the LinkedList head and other List methods, and StudentNode which is obviously, the Node class. Also I've attached the first test1.txt file as well.

import java.io.FileNotFoundException;
import java.util.*;
public class Assignment3 {
public static void main (String []args){
StudentList<StudentNode> myList = new StudentList<StudentNode>();

[Code] .....

I tried making a method that basically counts up the list recursively then a second method that counts down recursively and is supposed to stop once it hits the middle number, then print that node.

Attached File(s) : test1.txt (106bytes)

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Sep 30, 2014

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2. In jsp 1 , i have 3 checkboxes(chkbox1,chkbox2,chkbox3) , if i select check boxes (chkbox2, chkbox3), and click on submit, corresponding two text fields(chkbox2,chkbox3) will have to appear in the next jsp i.e., jsp 2.

Like this, which ever checkbox i select, corresponding text fields should appear in the subsequent jsp.

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May 15, 2014

Its that very old question regarding hashcode and equals implementation which i am not getting .

import java.util.*;

public class MyElement {
public static void main(String a[]){

HashSet<Price> lhm = new HashSet<Price>();
lhm.add(new Price("Banana", 20));
lhm.add(new Price("Apple", 40));

[Code] .....

In the above program even if i comment out the Hashcode method , i believe it is still taking the memory address values from the native hashcode method of Object class. but the equals override implentation says that i have two insertions which are same . So as per my logic it should not allow the duplicate element to enter.but its not so ...the duplicate element is well inserted without hashcode .

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So my code would be?

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class GridLayoutApplet extends Applet implements ActionListener{
// construct components
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TextField fNameField = new TextField(20);

[Code] .....

I have read about panels and frames but, it is all confusing to me. How can you add a label and a TextField to one square of the grid?

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Dec 26, 2014

Not necessarily Java related, more a general programming issue I have come a long and I am currently using java to mock up a project that will eventually get moved over to C++.

I am trying to implement FFT Convolution into a java project and have things partially working, I do not know if it is a coding issue, logic issue or if I simply know nothing of FFT and convolution.

For starters I got an FFT library that I do have working, if I create a small array pass it into the forward FFT, do a little bit of bit manipulation (converting a complex array of size n*2 into a re[] and im[] of size n), run the inverse FFT and do the same bit manipulation again I get back where I started.

However if I take two arrays, a Dirac Delta function (an array with a 1 followed by zeros for the rest of the array) and a stepping kernel (ex. {1, 2, 3, 4 etc}), I would expect to get the forward FFT of both arrays, bit manipulation, multiply them together, Inverse FFT, and bit manipulate again and the result would be the kernel. I have not had such luck.

This is the gist of the program:

// bit manipulation, converts complex array to two re and im arrays
public void bitTwiddle(double [] real, double [] real2, double [] imaginary){

double [] realCopy = new double [] {0, 0, 0, 0, 0, 0, 0, 0};
double [] imaginaryCopy = new double [] {0, 0, 0, 0, 0, 0, 0, 0};

for (int idx = 0; idx < (N * 2); idx++){
realCopy[idx] = real [idx];

[Code] ....

This is the result:

Quote
=====================================================================
Dirac Delta In Time Domain:
Real:1.000.000.000.00
Imag:0.000.000.000.00
=====================================================================
Dirac Delta Frequency Domain
Real:0.500.500.500.50
Imag:0.000.000.000.00
=====================================================================
Kernel In Time Domain
Real:1.002.003.004.00
Imag:0.000.000.000.00
=====================================================================
Kernel In Frequency Domain
Real:5.00-1.00-1.00-1.00
Imag:0.00-1.000.001.00
=====================================================================
Result: Dirac Delta x Kernel
Real:2.50-0.50-0.50-0.50
Imag:0.00-0.000.000.00
=====================================================================
Result In Time Domain
Real:0.501.501.501.50
Imag:0.000.000.00-0.00

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int age;
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[Code] ....

What exactly is happening behind the scenes? I don't understand mostly the part where it returns a 0, a 1, or a -1. After it returns one of those values, what really happens next?

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[Code] ....

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