Sieve Code To Find Prime Numbers
Jan 16, 2015
I am doing a sieve code to find prime numbers.
public static void main(String[] args)
{
Scanner scanner = new Scanner(System.in);
System.out.println(" Enter the maximum number ");
int maxNumber = scanner.nextInt();
int[]numberList = createList (maxNumber);
[code]....
I have a problem with the output. It only get as far as marking the multiples of 2. It does not mark the multiples of 3 and so on.Example output: If the range is from 2 to 15 the output is :2, 3, 0, 5, 0, 7, 0, 9, 0, 11, 0, 13, 0, 15 note: 0 means its marked.As you can see it only marks multiples of 2 but it does not mark multiples of 3 above. I think the problem lies in the for loop inside my main method, because the index does not increment.
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Oct 10, 2014
I want to find the prime palindrome numbers less that a given number by my program. Here is my code, I am trying to find the method to solve the errors when I compile it. It said variable a might not have been initialized in line 41,62,86.
import java.util.Scanner;
public class Lab5{
public static void main (String[] args){
System.out.println("Please input a number");
Scanner Input=new Scanner(System.in);
int num = Input.nextInt();
[Code]...
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Jun 20, 2014
the prime numbers from 1 to 2500 can be obtained as follows. From a list of the numbers of 1 to 2500,cross out al multiples of 2 (but not 2 itself). Then, find the next number (n, say) that is not crossed out and cross out all multiples of n (but not including n).
Repeat this last step provided that n has not exceeded 50 (the square root of 2500). The numbers remaining in the list (except 1) are prime. Write a program which uses this method to print all primes from 1 to 2500. Store your output in a file called primes.out.
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Aug 22, 2014
I tried to create file and write the output of my program in it in java when i use WriteLong then the file does not contain long value, how I create this file my program is to print prime numbers between 500000 to 10000000
public class primenumber {
public static void main(String[] args) {
long start = 5000000;
long end = 10000000;
System.out.println("List of prime numbers between " + start + " and " + end);
for (long i = start; i <= end; i++) {
if (isPrime(i)) {
System.out.println(i);
[Code] ....
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Oct 17, 2014
Program is to list all prime numbers between two entered numbers.
import java.util.Scanner;
public class question6 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter lower int:");
int x = input.nextInt();
[Code] .....
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Feb 13, 2015
The assignment is to make a program that prints the number of prime numbers in a range. This is what i have so far. The output is a list of 2s. I created the for loop to cycle through the range of 17-53 and nested a while loop within to test each incident of the for loop to check for divisors starting with 2 until the modulus result is 0 resulting in a false for being a prime number. Then the loop should increment to the next i value. The last part is an if statement that i had intended to add counters to the k variable that would keep track of the number of prime numbers.
boolean isPrime = true;
int j = 2;
int k = 1;
for (int i = 17; i <= 53; i++){
{
while (i % j == 0){
isPrime = false;
[Code] .....
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Dec 15, 2014
The challenge is to weed out all the prime numbers without using any kind of division (%, /). My code doesn't weed out certain numbers, such as many multiples of 5, the number 49, etc, and I am not sure why. Here is my code.
My logic for the for loops was this: Starting with the upper numbers of the ArrayList, find every number that is a multiple of that number and remove it from the ArrayList. Every time you find a multiple, increase the variable multiply, so the program knows what the next multiple to look for.
// program doesn't work yet.
import java.util.ArrayList;
// import java.util.ListIterator;
public class Sieve2
{
public static void main(String[] args)
{
int upperLimit = 55;
ArrayList<Integer> primes = new ArrayList<Integer>();
[Code] .....
And this is the output:
1 2 3 5 7 11 13 17 19 23 25 29 31 35 37 41 43 47 49 53 55
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May 2, 2014
Java program takes positive int from user and determine if prime. Next the program finds next highest or next lowest prime number.
import java.io.*;
import java.util.*;
public class pa2take2 {
public static void main (String[]args){
int menus; //menu selection
[Code] ......
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Oct 18, 2014
Program to pull prime numbers between two entered values,
import java.util.Scanner;
public class question6 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter lower int:");
[Code] ....
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Nov 7, 2014
The game doesn't seem to be working but you can win by loading a winning saved game.
Hint: Remember that all numbers have a unique set of Prime Factors.
I have been struggling to solve this. The code is not in error. I am trying to load a winning file but unable to solve.
Here is the java code:
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Random;
import java.util.Scanner;
import java.util.Set;
public class Main {
static final int GAME_SIZE = 40; //Disk sizes go from 0->39
// Produce a list of the first N prime numbers
[Code] ....
Results:
C:UsersSal_2>java Main
Welcome to Towers of Toast!!!
Type 'new' to start a new random puzzle
Type 'load' to load a saved puzzle
new
[0, 2, 3, 4, 5, 6, 8, 10, 14, 19, 20, 25, 26, 28, 35, 38, 39]
[7, 9, 11, 13, 15, 21, 22, 23, 27, 31, 32]
[1, 12, 16, 17, 18, 24, 29, 30, 33, 34, 36, 37]
|
|
XX |
|
XXX |
|
XXXX |
|
XXXXX |
|
XXXXXX |
X
XXXXXXXX XXXXXXX
XXXXXXXXXXXX
XXXXXXXXXX XXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXX XXXXXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The game is broken! We saved your game, though. Here are your save game numbers:
146209709250387100944095470
52067710192022655041
21882855117530023387473
C:UsersSal_2>java Main
Welcome to Towers of Toast!!!
Type 'new' to start a new random puzzle
Type 'load' to load a saved puzzle
load
Enter save number for pole 1:
3
Enter save number for pole 2:
1
Enter save number for pole 3:
11
Exception in thread "main" java.lang.RuntimeException: Not all disks accounted f
or
at Main.main(Main.java:100)
C:UsersSal_2>
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Aug 29, 2014
The code here I have works fine if I just want to ask the user to enter four digits: //java application that asks user to input binary numbers(1 or 0) and convert them to decimal numbers import java.util.Scanner; //program uses class scanner public class binarynumber{
//main method that executes the java application
public static void main(String args[]){
//declares variables
int digit;
int base=2;
int degree;
double decimal;
int binary_zero=0;
int binary_one=1;
//create scanner for object input
[code]....
The thing is, I want the java application to input more than four digits for the user and I want it to loop it manytimes f until the user ask it to stop.
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Nov 4, 2014
I have been struggling with this program for weeks. This program is supposed to take a user's inputted odd number and then print out all prime numbers lower than that number.
public class PrimeNumber
{
Scanner scan = new Scanner(System.in);
int userNum;
String neg;
public void getUserNum()
[code]...
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Feb 9, 2015
I am trying to figure out the Sieve of Eratosthenes program using arrays. I am trying to display the prime numbers of 1-100. My code right now is:
import java.text.DecimalFormat;
import java.util.Scanner;
public class TextLab06st
{
public static void main(String args[])
{
// This main method needs additions for the 100 point version.
Scanner input = new Scanner(System.in);
System.out.println("
TextLab06
[code]...
I am getting the error <identifier? expected for the line "primes.[index] = false;"
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Apr 1, 2015
When I compile the code, it goes through fine in the compiler. However after entering the boundaries for the lower an upper it doesn't produce the prime pairs between the two boundaries that the user sets. I have tried changing some of my integers that i initialized no luck. I looked at the last section of public void showPrimes() . However I can't seem to see where it has gone wrong there. I have included the entire code, plus the section again that I think is wrong. I have also posted the final output of what it looks like and what else should be included to make it easier to see what I am missing. Basically it keeps giving me zero primes even when the boundary is 100 and 200, or so and so forth.
import java.util.Scanner;
public class kbeaudry_xSieve
{
public static void main (String args[]){
kbeaudry_xSieve i = new kbeaudry_xSieve();
}
boolean primes[] = new boolean [50001];
int upper;
int lower;
[code]....
This is what i get when I actually run the program. However in the section where I have added *****, this is where it should put the prime pairs in.
Please enter a lower boundary and an upper boundary and I will print all of the sexy prime pairs between those boundaries.
Please enter the lower boundary (between 1 and 50000): 200
Please enter the upper boundary (between 1 and 50000): 600
There were 0 sexy pairs displayed between 200 and 600.. I am still working on another code for my that I had issues with, however I had to go out of the country for a few days to take care of some work.
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Jun 27, 2014
I found this method from the same link from which I found the Pandigital method. This method uses the algorithm of sieve of eratosthenes who was a greek mathematician and showed how to find prime numbers by taking an individual number and finding the multiples of it and cut them out for they will not be a prime number. From what I've seen this program gives the results much faster than the traditional way of searching for prime numbers by diving that number by the digits upto half of that number and check for divisiblity.
Well, here's the code
public int[] ESieve(int upperLimit) {
int sieveBound = (int)(upperLimit - 1) / 2;
int upperSqrt = ((int)Math.Sqrt(upperLimit) - 1) / 2;
BitArray PrimeBits = new BitArray(sieveBound + 1, true);
for (int i = 1; i <= upperSqrt; i++) {
if (PrimeBits.Get(i)) {
[Code] .....
As seen from the full program on the site [URL] .... this program was formely writen in C++ and from there I've scrapped out this method as the syntax are corresponding to that of Java, but one problem I faced was in finding the BitArray class in Java. I was unable to understand the approach of this program to find the prime numbers.
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May 23, 2014
So, if you are a football/soccer fan, you know that in every FIFA World Cup you have 4 nations. From those 4, 2 will qualify to the Knockout stages.
Let's say, after all the group fixtures are played, the standings are as follows :
1. England - 6 points
2. Spain - 4 points
3. Brasil - 3 points
4. Germany - 1 point
I want to know how I can select ONLY England and Spain for the Knockout stage of the FIFA World Cup (The class I am working on).
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Jun 17, 2014
Writing a Java program to find sum of numbers in a random string.
(Input=abc235^%$q!12&3 output=250)
If a number has - sign then u should consider it as a negative number.(Input=abc-12t%^&$dcf22 Output=10)
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Jan 23, 2015
I have to write a program that find the sum of two numbers 62 and 99 and stores them in a variable named total. However, I have one error that I just can't get rid of and can't tell what it is. I'm using jGrasp and here's what it says:
Programming Challenge #5.java:14: error: class SumofTwoNumbs is public, should be declared in a file named SumofTwoNumbs.java
public class SumofTwoNumbs {
^
1 error
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.
and here: is my code:
import java.util.Scanner;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
// This program has variable of several of the integer types.
public class SumofTwoNumbs {
public static void main(String[] args) {
[code]....
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Feb 23, 2014
im trying to do a program to find if numbers are consecutive or not! if they are consecutive i need a true as a return and a false when they are not... i did this program and im sure i did something wrong because i keep only true returns ..
Example: (3,5,7) (1,2,2) (7,7,9) should return a false!
Java Code: import java.util.*;
public class Consecutive{
public static void main (String [] args){
Scanner console= new Scanner(System.in);
System.out.println("Enter three numbers");
String numbers = console.nextLine();
System.out.println( "The numbers (" + numbers + ") is '" + consecutive( numbers ) + "'" );
}//end of main
[code]...
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Jan 27, 2015
The code is used to find coordinates of an image and i cannot understand how it works.
for (int y = 0; y < height; y += 2) {
for (int x = 0; x < width; x += 2) {
int px1 = secureRandom.nextInt(4);
int px2 = secureRandom.nextInt(4);
while (px1 == px2)
px2 = secureRandom.nextInt(4);
int px1x = (px1 < 2) ? px1 : px1 - 2;
int px1y = (px1 < 2) ? 0 : 1;
int px2x = (px2 < 2) ? px2 : px2 - 2;
int px2y = (px2 < 2) ? 0 : 1;
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Aug 23, 2014
Write a program to find maximum between three numbers using ternary operator.
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Feb 23, 2014
The program below is intended to find the arithmetic mean of the numbers stored in the array q in two ways: once by storing the numbers in an ArrayList d, where you allow all the necessary conversions to be performed automatically; and once by storing them in an ArrayList e, where you perform all the conversions by hand. Complete the program.
Here is what I have so far:
double[] q = { 0.5, 2.4, 7.4, 2.8, -6.2 };
ArrayList<Double> d = new ArrayList<Double>();
ArrayList<Double> e = new ArrayList<Double>();
for ( double x : q ) {
d.add( x );
e.add ( new Double ( x ) );
[Code] .....
Why does it still show "a / d.size?" I thought I fixed that. Whatever, it's supposed to be "dTotal / d.size()", etc.
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Oct 3, 2013
I should mention here that number of elements can be from 1....10'000. And it has to be done as O(N)
I attempted at the problem like so :
public static int adjacencies(int[] A) {
int count = 0;
boolean found = false;
for(int i = 0; i < A.length-1; i++) {
if (A[i] == A[i+1]) {
[Code] .....
To me it looks right and it seems to work.
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Jul 10, 2014
I need to find the largest value in a scanned file.I've gotten the count, sum, average, evens, and odds myself.The code above the while loop is not mine and my professor said I may no edit it or other wise mess with it. I also may not use arrays.Also I've realized that the largest/smallest are recording the value of count. I've tried the following:
Scanner infile = new Scanner ( new FileReader(args[0]) );
int count=0,sum=0, largest=Integer.MIN_VALUE,smallest=Integer.MAX_VALUE, evens=0, odds=0;
double average=0.0;
[code]....
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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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Feb 5, 2014
I am trying to find 3 largest numbers in an array using a single For loop but my following code is still showing randomly sorted numbers.
public class largest3 {
static int m, n, o;
static int array[] = new int[100];
public static void main(String[] args) {
for (int i = 0; i < 10; i++) {
array[i] = (int) (Math.random() * 100);
[Code] ....
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