Develop Reference

How to send from deque and split it into two lists?

Hello everyone I was given the assignment in which I have
In main, you create a queue with generated Strings
word genereting should be done in main
You pass it to executeTasks, they are split into the appropriate lists
I have a problem with referencing things in code
it is still confusing for me☹️
it was much easier on the numbers
Write a program that in the ArrayDeque queue will put 50 objects storing strings (strings), consisting of the letter 'a' repeated a random number of times (repeat range: 1-50).
Filling the object with the repeats of the letter 'a' can be done with a for loop.
Part 2
Extend the program from the first part in such a way that you pass the created queue to the method of your class, which will separate the objects from the queue into two ArrayList collections.
One of them will hold objects with an even number of 'a' characters, the other one with an odd number.
in general, I have done the task in a slightly different way, but I need to correct it
import java.util.*;
import java.lang.*;
class TaskManager {
List<String> executedTasks;
List<String> even;
List<String> odd;
// constructor
public TaskManager() {
executedTasks = new ArrayList<>();
even = new ArrayList<>();
odd = new ArrayList<>();
}
//method serving the list of tasks
public void executeTasks(Deque<String> theQueue) {
while (theQueue.size() > 0) {
String theTask = theQueue.poll();
System.out.println("Processing the task: " + theTask);
char c = 'a';
for (int n = 0; n < 50; n++) {
String result = "";
int count = (char) (Math.random() * 50 + 1);
for (int i = 0; i < count; i++) {
result += c;
}
System.out.println(result);
if (result.length() % 2 == 0) {
even.add(result);
} else {
odd.add(result);
}
executedTasks.add(theTask);
System.out.println("\nExecuted total " + executedTasks.size() + " tasks\n");
}
}
}
}
/* Name of the class has to be "Main" only if the class is public. */
public class QueuesAndLoops {
public static void main(String[] args) throws java.lang.Exception {
char c = 'a';
Deque<String> taskQueue1 = new ArrayDeque<>();
for (int n = 0; n < 1; n++) {
taskQueue1.offer("The first task number " + (n + 1));
}
TaskManager taskExecutor = new TaskManager();
taskExecutor.executeTasks(taskQueue1);
System.out.println("Parzyste:");
System.out.println(taskExecutor.even);
System.out.println("Nieparzyste:");
System.out.println(taskExecutor.odd);
}
}
and this code works but I have a problem to change it to the required version

no one replied but it was about reworking it in a similar way
import java.util.*;
import java.lang.*;
class TaskManager {
List<String> even;
List<String> odd;
// constructor
public TaskManager() {
even = new ArrayList<>();
odd = new ArrayList<>();
}
//method serving the list of tasks
public void executeTasks(Deque<String> theQueue) {
String task;
while ((task = theQueue.poll()) != null) {
System.out.println(task);
boolean isAdded = task.length() % 2 == 0 ? even.add(task) : odd.add(task);
}
}
}
public class QueuesAndLoops {
public static void main(String[] args) throws java.lang.Exception {
final int NUM_TASKS = 50;
String chr = "a";
Deque<String> taskQueue1 = new ArrayDeque<>();
for (int i = 0; i < NUM_TASKS; i++) {
taskQueue1.offer(chr.repeat((int) (Math.random() * 50 + 1)));
}
TaskManager taskExecutor = new TaskManager();
taskExecutor.executeTasks(taskQueue1);
System.out.println("Even:");
System.out.println(taskExecutor.even);
System.out.println("Odd:");
System.out.println(taskExecutor.odd);
}
}

Making a recursive method to print a text in java

I have to make a program which works like this. first it gets a number from input and then it gets (number) * strings.
for example:
2
a b
or
3
x1 x2 x3
then in the output it prints something like this:
Math.max(a, b)
or
Math.max(x1, Math.max(x2, x3))
I want to make Math.max method syntax with this code. I hope you understood!
Another Sample Input & output:
Input =
4
a b c d
Output =
Math.max(a, Math.max(b, Math.max(c, d)))
can someone help me?
The code I've wrote for it, can you suggest me some changes to make it better?
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int n = input.nextInt();
String[] r = new String[n];
for (int i = 0; i < n; i++) {
r[i] = input.next();
}
printmax(r);
}
public static int i = 0 , j = 0;
public static boolean last = false;
public static void printmax(String [] r){
if (last == true) {
System.out.print(r[r.length - 1]);
while (j < r.length - 1){ System.out.print(")");
j++;
}
}
if (r.length == 2) System.out.print("Math.max(" +r[0] + ", " + r[1] + ")");
if (r.length > 2) {
while (i < r.length -1) {
if (i == r.length -2) last = true;
System.out.print("Math.max(" + r[i] + ", ");
i++;
printmax(r);
}
}
}
}

You can use the following code to achieve the above, here m calling maxElement() function recursively to achieve somthing like this Math.max(a, Math.max(b, Math.max(c, d)))
public static void main(String args[]){
int length = 2; //here read the input from scanner
String[] array = {"a", "b"}; //here read this input from scanner
String max = maxElement(array,0,length);
System.out.println(max);
}
public static String maxElement(String[] start, int index, int length) {
if (index<length-1) {
return "Math.max(" + start[index] + ", " + maxElement(start, index+1, length)+ ")";
} else {
return start[length-1];
}
}
Output:
Math.max(a, b)

You need to do something like this.
First you define a function maxElement which takes your variable array as a parameter.
public static maxElement(String[] variables) {
return maxElementBis(variables,0);
}
Then you call a second function : maxElementBis which takes an additional argument which represents the index of the variable we are processing.
public static String maxElementBis(String[] variables, int index) {
if (variables.length < 2)
return "not enought variables";
if (variables.length - index == 2)
return "Math.max("+ variables[index]+","+variables[index + 1]+")";
return "Math.max("+ variables[index]+","+maxElementBis(variables,index + 1)+")";
}
If the array contains less than two variables you cannot do what you want.
If you only have two variables left, this is your stop condition and you can directly return Math.max(v1,v2).
Otherwise you recursively call your function maxElementBis.

Copying Object in Java

So I've been tasked to work on an algorithm based on Random Mutation Hill Climbing. I have a method RMHC that takes in an ArrayList of weights and two ints, one for number of weights and another for iterations. My instructions tell me to create an initial solution, copy it and then apply a mutation method SmallChange() to the initial solution. I was also instructed on how to copy the solution with the GetSol() method in my ScalesSolution class. The mutation takes in a binary String value (i.e 11101) and changes a random substring in the binary to either 0 or 1 so I may be met with an output such as 10101 if the 2nd substring is mutated.
My issue is that when I make the SmallChange() to my solution, it makes the change to the original solution also.
I've already tried adding a copy constructor as what was suggested in another question I'd found, but it did not work.
Main Method
public class Worksheet9 {
public static void main(String[] args) {
ArrayList<Double> myArray = new ArrayList<Double>();
myArray.add(1.0);
myArray.add(2.0);
myArray.add(3.0);
myArray.add(4.0);
myArray.add(10.0);
RMHC(myArray, 5, 2);
}
RMHC Method
public static ScalesSolution RMHC(ArrayList<Double> weights,int n,int iter)
{
ScalesSolution oldsol = new ScalesSolution(n);
ScalesSolution newsol = new ScalesSolution(oldsol.GetSol());
//Attempting Copy Constructor
ScalesSolution newsol = new ScalesSolution(oldsol);
double origfitness = oldsol.ScalesFitness(weights);
System.out.println("Original Fitness: " + origfitness);
double origfitness1 = newsol.ScalesFitness(weights);
System.out.println("Cloned Original Fitness: " + origfitness1);
newsol.SmallChange();
double origfitness2 = newsol.ScalesFitness(weights);
System.out.println("Changed Fitness: " + origfitness2);
double origfitness3 = oldsol.ScalesFitness(weights);
System.out.println("Cloned Original Fitness: " + origfitness3);
return(oldsol);
}
}
ScalesSolution Class
import java.util.ArrayList;
import java.util.Random;
public class ScalesSolution
{
private static String scasol;
//Creates a new scales solution based on a string parameter
//The string parameter is checked to see if it contains all zeros and ones
//Otherwise the random binary string generator is used (n = length of parameter)
#
public ScalesSolution(ScalesSolution another) {
this.scasol = another.scasol; // you can access
}
public void SmallChange() {
int n = scasol.length();
String s = scasol;
Random rand = new Random();
int p = (rand.nextInt(n));
String x;
x = scasol.substring(0, p);
if (scasol.charAt(p) == '0') {
x += '1';
} else {
x += '0';
}
x += scasol.substring(p + 1, n);
scasol = x;
}
public String GetSol()
{
return(scasol);
}
public ScalesSolution(String s)
{
boolean ok = true;
int n = s.length();
for(int i=0;i<n;++i)
{
char si = s.charAt(i);
if (si != '0' && si != '1') ok = false;
}
if (ok)
{
scasol = s;
}
else
{
scasol = RandomBinaryString(n);
}
}
private static String RandomBinaryString(int n)
{
String s = new String();
//Code goes here
//Create a random binary string of just ones and zeros of length n
for(int i = 0; i < n; i++){
int x = CS2004.UI(0, 1);
if(x == 0){
s += '0';
} else if (x == 1) {
s += '1';
}
}
return(s);
}
public ScalesSolution(int n)
{
scasol = RandomBinaryString(n);
}
//This is the fitness function for the Scales problem
//This function returns -1 if the number of weights is less than
//the size of the current solution
public static double ScalesFitness(ArrayList<Double> weights)
{
if (scasol.length() > weights.size()) return(-1);
double lhs = 0.0,rhs = 0.0;
int n = scasol.length();
for(int i = 0; i < n; i++){
if (scasol.charAt(i) == '0') {
lhs += weights.get(i);
}
else {
rhs += weights.get(i);
}
}
//Code goes here
//Check each element of scasol for a 0 (lhs) and 1 (rhs) add the weight wi
//to variables lhs and rhs as appropriate
return(Math.abs(lhs-rhs));
}
//Display the string without a new line
public void print()
{
System.out.print(scasol);
}
//Display the string with a new line
public void println()
{
print();
System.out.println();
}
}
When I call the RMHC function in the main method, I get an output like this:
Original Fitness: 16.0
Cloned Original Fitness: 16.0
Changed Fitness: 14.0
Cloned Original Fitness: 14.0
The 2nd Cloned Original Fitness should also be value 16.0 in this example. Once I figure out this initial issue, I will implement the code into a for loop to include the iterations. Thanks.

Assuming this is where you try to copy your data:
ScalesSolution oldsol = new ScalesSolution(n);
ScalesSolution newsol = new ScalesSolution(oldsol.GetSol());
This doesn't work because the variable is static:
public class ScalesSolution
{
private static String scasol;
//...
public String GetSol()
{
return(scasol);
}
Since all you do is assign the value to the static string scasol, no actual change or copy is made.

Java Fitness Function - Scales

I have a fitness function as part of a lab and wish to apply it to a set of 'weights' (ArrayList weights). I have created the array and stored some values in it. I have created random binary strings (which have an 'x' at the end in order to generate random values) which I wish to also apply the fitness function to; however, the problem I am having is that the fitness function always returns a value of 0. Am I missing something here?
The fitness function is as follows:
import java.util.*;
public class ScalesSolution{
private static String scasol;
//Creates a new scales solution based on a string parameter
//The string parameter is checked to see if it contains all zeros and ones
//Otherwise the random binary string generator is used (n = length of parameter)
public ScalesSolution(String s)
{
boolean ok = true;
int n = s.length();
for(int i=0;i<n;++i)
{
char si = s.charAt(i);
if (si != '0' && si != '1') ok = false;
}
if (ok)
{
scasol = s;
}
else
{
scasol = RandomBinaryString(n);
}
}
private static String RandomBinaryString(int n)
{
String s = new String();
//Code goes here
//Create a random binary string of just ones and zeros of length n
for(int i = 0; i < n; i++){
int x = CS2004.UI(0,1);
if(x == 0){
System.out.print(s + '0');
}
else if(x == 1){
System.out.print(s + '1');
}
}
return(s);
}
public ScalesSolution(int n)
{
scasol = RandomBinaryString(n);
}
//This is the fitness function for the Scales problem
//This function returns -1 if the number of weights is less than
//the size of the current solution
//EXERCISE 3
public static double ScalesFitness(ArrayList<Double> weights)
{
int n = scasol.length();
double lhs = 0.0, rhs = 0.0;
if (n > weights.size()) return(-1);
for(int i = 0; i < n; i++){
if(scasol.charAt(i) == 0){
lhs += weights.get(i);
}
else{
rhs += weights.get(i);
}
}
//Code goes here
//Check each element of scasol for a 0 (lhs) and 1 (rhs) add the weight wi
//to variables lhs and rhs as appropriate
return(Math.abs(lhs-rhs));
}
//Display the string without a new line
public void print()
{
System.out.print(scasol);
}
//Display the string with a new line
public void println()
{
print();
System.out.println();
}}
Main method (in separate class):
import java.util.ArrayList;
public class Lab8 {
public static void main(String args[])
{
for(int i = 0; i < 10; i++){
ScalesSolution s = new ScalesSolution("10101x");
s.println();
}
ArrayList<Double> weights = new ArrayList<Double>();
weights.add(1.0);
weights.add(2.0);
weights.add(3.0);
weights.add(4.0);
weights.add(10.0);
System.out.println();
System.out.println(weights);
System.out.print("Fitness: ");
double fitness = ScalesSolution.ScalesFitness(weights);
System.out.println(fitness);
}}
CS2004 class:
import java.util.*;
import java.io.*;
//Some useful code that we will probably reuse in later laboratories...
public class CS2004
{
//Shared random object
static private Random rand;
//Create a uniformly distributed random integer between aa and bb inclusive
static public int UI(int aa,int bb)
{
int a = Math.min(aa,bb);
int b = Math.max(aa,bb);
if (rand == null)
{
rand = new Random();
rand.setSeed(System.nanoTime());
}
int d = b - a + 1;
int x = rand.nextInt(d) + a;
return(x);
}
//Create a uniformly distributed random double between a and b inclusive
static public double UR(double a,double b)
{
if (rand == null)
{
rand = new Random();
rand.setSeed(System.nanoTime());
}
return((b-a)*rand.nextDouble()+a);
}
//This method reads in a text file and parses all of the numbers in it
//This code is not very good and can be improved!
//But it should work!!!
//It takes in as input a string filename and returns an array list of Doubles
static public ArrayList<Double> ReadNumberFile(String filename)
{
ArrayList<Double> res = new ArrayList<Double>();
Reader r;
try
{
r = new BufferedReader(new FileReader(filename));
StreamTokenizer stok = new StreamTokenizer(r);
stok.parseNumbers();
stok.nextToken();
while (stok.ttype != StreamTokenizer.TT_EOF)
{
if (stok.ttype == StreamTokenizer.TT_NUMBER)
{
res.add(stok.nval);
}
stok.nextToken();
}
}
catch(Exception E)
{
System.out.println("+++ReadFile: "+E.getMessage());
}
return(res);
}}
Once run, the random binary strings work perfectly well, yet the fitness function fails to change from 0. Here is a sample output:
011100
111010
001110
111011
001000
010101
001010
100011
110100
011001
[1.0, 2.0, 3.0, 4.0, 10.0]
Fitness: 0.0
Thank you all so much for your time.
Stefanos.

scasol appears to be empty when ScalesFitness is called. In the RandomBinaryString method, you never actually construct s, but rather, just print it out. Instead of System.out.print(s+'0') and the other line, you should have s += '0';.
Since this appears to be an exercise, I'll leave the rest to you, but here is a tip for next time: don't have a function do more than it's supposed to (such as printing out its results), otherwise, it might look like the set of functions is actually working, when in reality it isn't.
In this case, it looked like everything was working fine since it appeared like the s.println() function what actually printing out scasol, but in reality, scasol was empty and the RandomBinaryString method was actually doing the printing.

Uva's 3n+1 problem

I'm solving Uva's 3n+1 problem and I don't get why the judge is rejecting my answer. The time limit hasn't been exceeded and the all test cases I've tried have run correctly so far.
import java.io.*;
public class NewClass{
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException {
int maxCounter= 0;
int input;
int lowerBound;
int upperBound;
int counter;
int numberOfCycles;
int maxCycles= 0;
int lowerInt;
BufferedReader consoleInput = new BufferedReader(new InputStreamReader(System.in));
String line = consoleInput.readLine();
String [] splitted = line.split(" ");
lowerBound = Integer.parseInt(splitted[0]);
upperBound = Integer.parseInt(splitted[1]);
int [] recentlyused = new int[1000001];
if (lowerBound > upperBound )
{
int h = upperBound;
upperBound = lowerBound;
lowerBound = h;
}
lowerInt = lowerBound;
while (lowerBound <= upperBound)
{
counter = lowerBound;
numberOfCycles = 0;
if (recentlyused[counter] == 0)
{
while ( counter != 1 )
{
if (recentlyused[counter] != 0)
{
numberOfCycles = recentlyused[counter] + numberOfCycles;
counter = 1;
}
else
{
if (counter % 2 == 0)
{
counter = counter /2;
}
else
{
counter = 3*counter + 1;
}
numberOfCycles++;
}
}
}
else
{
numberOfCycles = recentlyused[counter] + numberOfCycles;
counter = 1;
}
recentlyused[lowerBound] = numberOfCycles;
if (numberOfCycles > maxCycles)
{
maxCycles = numberOfCycles;
}
lowerBound++;
}
System.out.println(lowerInt +" "+ upperBound+ " "+ (maxCycles+1));
}
}

Are you making sure to accept the entire input? It looks like your program terminates after reading only one line, and then processing one line. You need to be able to accept the entire sample input at once.

I faced the same problem. The following changes worked for me:
Changed the class name to Main.
Removed the public modifier from the class name.
The following code gave a compilation error:
public class Optimal_Parking_11364 {
public static void main(String[] args) {
...
}
}
Whereas after the changes, the following code was accepted:
class Main {
public static void main(String[] args) {
...
}
}
This was a very very simple program. Hopefully, the same trick will also work for more complex programs.

If I understand correctly you are using a memoizing approach. You create a table where you store full results for all the elements you have already calculated so that you do not need to re-calculate results that you already know (calculated before).
The approach itself is not wrong, but there are a couple of things you must take into account. First, the input consists of a list of pairs, you are only processing the first pair. Then, you must take care of your memoizing table limits. You are assuming that all numbers you will hit fall in the range [1...1000001), but that is not true. For the input number 999999 (first odd number below the upper limit) the first operation will turn it into 3*n+1, which is way beyond the upper limit of the memoization table.
Some other things you may want to consider are halving the memoization table and only memorize odd numbers, since you can implement the divide by two operation almost free with bit operations (and checking for even-ness is also just one bit operation).

Did you make sure that the output was in the same order specified in the input. I see where you are swapping the input if the first input was higher than the second, but you also need to make sure that you don't alter the order it appears in the input when you print the results out.
ex.
Input
10 1
Output
10 1 20

If possible Please use this Java specification : to read input lines
http://online-judge.uva.es/problemset/data/p100.java.html
I think the most important thing in UVA judge is 1) Get the output Exactly same , No Extra Lines at the end or anywhere . 2) I am assuming , Never throw exception just return or break with No output for Outside boundary parameters.
3)Output is case sensitive 4)Output Parameters should Maintain Space as shown in problem
One possible solution based on above patterns is here
https://gist.github.com/4676999
/*
Problem URL: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=36
Home>Online Judge > submission Specifications
Sample code to read input is from : http://online-judge.uva.es/problemset/data/p100.java.html
Runtime : 1.068
*/
import java.io.*;
import java.util.*;
class Main
{
static String ReadLn (int maxLg) // utility function to read from stdin
{
byte lin[] = new byte [maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read();
if ((car < 0) || (car == '\n')) break;
lin [lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)) return (null); // eof
return (new String (lin, 0, lg));
}
public static void main (String args[]) // entry point from OS
{
Main myWork = new Main(); // create a dinamic instance
myWork.Begin(); // the true entry point
}
void Begin()
{
String input;
StringTokenizer idata;
int a, b,max;
while ((input = Main.ReadLn (255)) != null)
{
idata = new StringTokenizer (input);
a = Integer.parseInt (idata.nextToken());
b = Integer.parseInt (idata.nextToken());
if (a<b){
max=work(a,b);
}else{
max=work(b,a);
}
System.out.println (a + " " + b + " " +max);
}
}
int work( int a , int b){
int max=0;
for ( int i=a;i<=b;i++){
int temp=process(i);
if (temp>max) max=temp;
}
return max;
}
int process (long n){
int count=1;
while(n!=1){
count++;
if (n%2==1){
n=n*3+1;
}else{
n=n>>1;
}
}
return count;
}
}

Please consider that the integers i and j must appear in the output in the same order in which they appeared in the input, so for:
10 1
You should print
10 1 20

package pandarium.java.preparing2topcoder;/*
* Main.java
* java program model for www.programming-challenges.com
*/
import java.io.*;
import java.util.*;
class Main implements Runnable{
static String ReadLn(int maxLg){ // utility function to read from stdin,
// Provided by Programming-challenges, edit for style only
byte lin[] = new byte [maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read();
if ((car < 0) || (car == '\n')) break;
lin [lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)) return (null); // eof
return (new String (lin, 0, lg));
}
public static void main(String args[]) // entry point from OS
{
Main myWork = new Main(); // Construct the bootloader
myWork.run(); // execute
}
public void run() {
new myStuff().run();
}
}
class myStuff implements Runnable{
private String input;
private StringTokenizer idata;
private List<Integer> maxes;
public void run(){
String input;
StringTokenizer idata;
int a, b,max=Integer.MIN_VALUE;
while ((input = Main.ReadLn (255)) != null)
{
max=Integer.MIN_VALUE;
maxes=new ArrayList<Integer>();
idata = new StringTokenizer (input);
a = Integer.parseInt (idata.nextToken());
b = Integer.parseInt (idata.nextToken());
System.out.println(a + " " + b + " "+max);
}
}
private static int getCyclesCount(long counter){
int cyclesCount=0;
while (counter!=1)
{
if(counter%2==0)
counter=counter>>1;
else
counter=counter*3+1;
cyclesCount++;
}
cyclesCount++;
return cyclesCount;
}
// You can insert more classes here if you want.
}

This solution gets accepted within 0.5s. I had to remove the package modifier.
import java.util.*;
public class Main {
static Map<Integer, Integer> map = new HashMap<>();
private static int f(int N) {
if (N == 1) {
return 1;
}
if (map.containsKey(N)) {
return map.get(N);
}
if (N % 2 == 0) {
N >>= 1;
map.put(N, f(N));
return 1 + map.get(N);
} else {
N = 3*N + 1;
map.put(N, f(N) );
return 1 + map.get(N);
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
try {
while(scanner.hasNextLine()) {
int i = scanner.nextInt();
int j = scanner.nextInt();
int maxx = 0;
if (i <= j) {
for(int m = i; m <= j; m++) {
maxx = Math.max(Main.f(m), maxx);
}
} else {
for(int m = j; m <= i; m++) {
maxx = Math.max(Main.f(m), maxx);
}
}
System.out.println(i + " " + j + " " + maxx);
}
System.exit(0);
} catch (Exception e) {
}
}
}