doburomirushii nikku

Yeah I mean log(base 8) 2. Thanks for the reply...I will look that up and see if it helps.

Edit: Figured it out...

public static int floorLog(int base, int value) { if (value == 1) { return 0; } if (base == value) { return 1; } if (value < base) { return 0; } else { value = value / base; return 1 + floorLog(base, value); } }
[ April 10, 2006: Message edited by: doburomirushii nikku ]

I'm trying to do a recursion that will find log 2^8 and return 3. Also if it gets log 2^15 it should return 3 also (so it rounds it down). Then I want to design a similar recusion method that will only find a perfect log such as log 2^8 = 3, but return -1 for log 2^15.

Here is my code for it.
public static int floorLog(int base, int value) { if (value == 1) { return 0; } if (base == value) { return 1; } else { return 1 + floorLog(base * base, value); } }

I know you need a base case for recusion so that would be if the value was 1...then whatever the base is would have to be rasied to the 0 power. Then there is also if base == value...The method would return 1.

But I'm now really sure how my recursion case should go. I understand that what I'm doing is going to do 2, then 2 * 2, then 4 * 4, ect., which is incorrect. So how can I preserve the base value?

I think I want the method to do this:

1 + floorLog(2, 8)
1 + floorLog(2 * 2, 8)
1 + floorlog(2 * 2 * 2, 8)
At this point I want it to return in my base case...I'm just not sure how to translate it recursively.

Thanks.

Edit: I forgot...I need to do it without importing java.math
[ April 10, 2006: Message edited by: doburomirushii nikku ]

I got it to work using your advice.

Talked it through and realized that since the square root of 9 was three it would skip the for loop and denote it as prime. Then I realized like you hinted at, that the for loop had to be inclusive.

Thanks for all the help everyone. The best part is that I really understand how to do this problem now!

Um...I still don't know how to make number go up right...

Here is the code I have now...

public class NthPrime { public static void main(String []args) { int nthprime, //input. prime, //keeps track of when a prime # is found. number = 0; //represents integers starting at 3. boolean isPrime = true; nthprime = IO.readInt(); if (nthprime <= 0) { IO.reportBadInput(); } if (nthprime == 1) { IO.printInt(2); } else if (nthprime == 2) { IO.printInt(3); } else { prime = 2; number = 3; while (prime < nthprime) { for (int i = 3; i < Math.sqrt(number); i++) { if (number % i == 0) { isPrime = false; number+=2; } } if (isPrime = true) { prime+=1; number+=2; } } IO.printInt(number); } } }

Hello,

I have to make a program that finds the nth prime number. Basically, the user types in a number, for example, 10 and the program outputs 29 (the 10th prime number).

I have created my program and I think I must be on the right track since when I input 10 the program outputs 28. The actual output is always a few numbers off the expected output and as you go higher...say you input 12, the program will output 32 as opposed to 37.

I think it is something to do with the way I increment my "number" value and I have played with it to make it go through the numbers as I want but have had no luck.

public class NthPrime { public static void main(String []args) { int nthprime, //input. prime, //keeps track of when a prime # is found. number = 0; //represents integers starting at 3. boolean isPrime = true; nthprime = IO.readInt(); if (nthprime <= 0) { IO.reportBadInput(); } //I figured I would get the first on out of the way. if (nthprime == 1) { IO.printInt(2); } //other wise use this loop the goes through each number //and checks if it is prime until "prime" is equal to "nthprime". else { prime = 1; number = 3; while (prime < nthprime) { for (int i = 2; i < number; i++) { if (number % i == 0) { isPrime = false; number+=1; } } if (isPrime = true) { prime+=1; number+=1; } } } IO.printInt(number); } }

basically, this program reads a list of numbers from a text file and then takes the factorial of each of those numbers. I got everything to work except the factorials are kinda off. They display the wrong values.

import java.awt.*; import java.awt.event.*; import java.io.*; import javax.swing.*; import java.lang.*; import java.math.*; public class FractorialMadness { int textInt; public static void main(String args[]) { File name = new File("h:/java/p1/p1.txt"); try { BufferedReader input = new BufferedReader(new FileReader(name)); StringBuffer buffer = new StringBuffer(); String text; int n; BigInteger nFact = BigInteger.ONE; //int nFactorial = 0; while( (text=input.readLine())!= null) { n = Integer.parseInt( text ); for ( int i = 1; i <= n; i++ ) { nFact = nFact.multiply(BigInteger.valueOf(i)); } System.out.println( n + " " + nFact ); } } catch (IOException io) { System.err.println("File error"); } } }

// Java core packages import java.awt.*; import java.awt.event.*; // Java extension packages import javax.swing.*; public class BlackJack extends JApplet implements ActionListener { private Image card[] = new Image[53]; int cards[] = new int[53]; int suits[] = new int[53]; int hold,b,a,i,j,x,y,xpos,playerTotal, dealerTotal; int player = 2; boolean firstTurn = true; JButton hitButton, standButton; public void init() { Container container = getContentPane(); container.setLayout( new FlowLayout() ); hitButton = new JButton( "Hit" ); hitButton.addActionListener( this ); container.add( hitButton ); standButton = new JButton( "Stand" ); standButton.addActionListener( this ); container.add( standButton ); createDeck(); shuffleCards(); //Start play drawCards(); drawCardsPlayer(); //End play, then reshuffle; }//End public void init public void paint( Graphics g ) { int x1Pos = -50; int x2Pos = 810; setSize (1000, 500); for ( int i = j; i < j+2; i++ ) { x1Pos = x1Pos + 50; g.drawImage( card[i], x1Pos, 0, this ); } for ( int a = b; a < b+2; a++ ) { x2Pos = x2Pos - 50; g.drawImage( card[a], x2Pos, 200, this ); } } public void actionPerformed( ActionEvent event ) { if ( ( event.getSource() == hitButton ) && ( playerTotal <= 21 ) && ( player == 2 ) ) { hitCardsPlayer(); } else if ( ( event.getSource() == standButton ) ) { player = 1; } //if ( dealerTotal <= 16 ) //hitCards(); } public void createDeck() { for ( int cardNumber = 1; cardNumber < 53; cardNumber++ ) { j = 1 + ( int ) ( Math.random() * 52 ); cards[cardNumber] = cardNumber % 13 + 1; suits[cardNumber] = cardNumber % 4; } }//End public void createDeck public void drawCards() { j++; //card = getImage( getDocumentBase(), "" ); for ( int i = j; i < j+2; i++ ) { if ( suits[i] == 0 ) System.out.println( cards[i] + " " + "HEARTS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofhearts.jpg" ); if ( suits[i] == 1 ) System.out.println( cards[i] + " " + "DIAMONDS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofdiamonds.jpg" ); if ( suits[i] == 2 ) System.out.println( cards[i] + " " + "CLUBS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofclubs.jpg" ); if ( suits[i] == 3 ) System.out.println( cards[i] + " " + "SPADES" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofspades.jpg" ); dealerTotal = dealerTotal + cards[i]; if ( cards[i] > 10 ) { int d = cards[i] - 10; dealerTotal = dealerTotal-d; } } }//End public void drawCards public void drawCardsPlayer() { b++; //card2 = getImage( getDocumentBase(), "" ); for ( int a = b; a < b+2; a++ ) { if ( suits[a] == 0 ) System.out.println( cards[a] + " " + "HEARTS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofhearts.jpg" ); if ( suits[a] == 1 ) System.out.println( cards[a] + " " + "DIAMONDS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofdiamonds.jpg" ); if ( suits[a] == 2 ) System.out.println( cards[a] + " " + "CLUBS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofclubs.jpg" ); if ( suits[a] == 3 ) System.out.println( cards[a] + " " + "SPADES" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofspades.jpg" ); playerTotal = playerTotal + cards[a]; if ( cards[a] > 10 ) { int d = cards[a] - 10; playerTotal = playerTotal-d; } } }//End public void drawCards public void hitCards() { j++; //card = getImage( getDocumentBase(), "" ); for ( int i = j; i < j+1; i++ ) { if ( suits[i] == 0 ) System.out.println( cards[i] + " " + "HEARTS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofhearts.jpg" ); if ( suits[i] == 1 ) System.out.println( cards[i] + " " + "DIAMONDS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofdiamonds.jpg" ); if ( suits[i] == 2 ) System.out.println( cards[i] + " " + "CLUBS" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofclubs.jpg" ); if ( suits[i] == 3 ) System.out.println( cards[i] + " " + "SPADES" ); card[i] = getImage( getDocumentBase(), cards[i] + "ofspades.jpg" ); if ( cards[i] > 10 ) { int d = cards[i] - 10; dealerTotal = dealerTotal-d; } } }//End public void drawCards public void hitCardsPlayer() { b++; //card2 = getImage( getDocumentBase(), "" ); for ( int a = b; a < b+1; a++ ) { if ( suits[a] == 0 ) System.out.println( cards[a] + " " + "HEARTS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofhearts.jpg" ); if ( suits[a] == 1 ) System.out.println( cards[a] + " " + "DIAMONDS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofdiamonds.jpg" ); if ( suits[a] == 2 ) System.out.println( cards[a] + " " + "CLUBS" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofclubs.jpg" ); if ( suits[a] == 3 ) System.out.println( cards[a] + " " + "SPADES" ); card[a] = getImage( getDocumentBase(), cards[a] + "ofspades.jpg" ); playerTotal = playerTotal + cards[a]; if ( cards[a] > 10 ) { int d = cards[a] - 10; playerTotal = playerTotal-d; } } }//End public void drawCards public void shuffleCards() { for ( int i = 1; i < 53; i++ ) { int j = 1 + ( int ) ( Math.random() * 52 ); hold = cards[i]; cards[i] = cards[j]; cards[j] = hold; hold = suits[i]; suits[i] = suits[j]; suits[j] = hold; } }//End public void shuffleCards }

ok so far it draws to cards for the dealer and player and displays the pictures on the applet. Then when i press hit, it will draw a new card, however it wont show the picture. It also displays only pictures of in spade cards. So it may display to 10 of spades when 10 of hearts and 10 or diamonds is drawn from the deck, for some reason. Any help, thank you.

Thanks for anyone who posted!

I really liked how david explained it though, and it was pretty easy. I think im starting to understand arrays better.

this is what i have now

// Java core packages import java.awt.*; import java.awt.event.*; // Java extension packages import javax.swing.*; public class Cards extends JApplet { int cards[] = new int[53]; int x,y,j,hold, cardSuit; public void init() { for ( int cardNumber = 1; cardNumber < 53; cardNumber++ ) { do { j = 1 + ( int ) ( Math.random() * 52 ); cards[cardNumber] = cardNumber % 13 + 1; } while ( cardNumber == j ); System.out.println( cards[cardNumber] ); } System.out.println(); System.out.println(); for ( int i = 1; i < 53; i++ ) { int j = 1 + ( int ) ( Math.random() * 52 ); hold = cards[i]; cards[i] = cards[j]; cards[j] = hold; cardSuit = i % 4; System.out.println( cards[i] + " " + cardSuit ); } } }

after the first loop runs, i have 4 of every card..but in the second loop somehow im getting duplicates. and card suit is just takin the remainder if its 0 and then that would be one suit, 1, 2, 3 would be the four suits.

ok..this outputs random..but then there is the issue of repeats im stuck on.

// Java core packages import java.awt.*; import java.awt.event.*; // Java extension packages import javax.swing.*; public class cards extends JApplet { int cards[] = new int[53]; int x,y,hold; public void init() { for ( int cardNumber = 1; cardNumber < 53; cardNumber++ ) { cards[cardNumber] = 1 + ( int ) ( Math.random() * 13 ); y = 1 + ( int ) ( Math.random() * 13 ); System.out.println( cards[cardNumber] + "-" + y + " " ); } } }

eh thank..Is there a way to do it without this though? I'm not really understanding this.

I'm not sure how to use collection..it says varible not found when i put it in.

im trying to deal out a 52 card deck of cards, randomly.. They have their card number and th suit attached to them. Can someone direct me in a better direction..I dont feel like im getting anywhere.

// Java core packages import java.awt.*; import java.awt.event.*; // Java extension packages import javax.swing.*; public class Cards extends JApplet { int cards[] = new int[52]; int x,y; public void init() { for ( int cardSuit = 1; cardSuit < 5; cardSuit++ ) { for ( int cardNumber = 1; cardNumber < 14; cardNumber++ ) { y = 1 + ( int ) ( Math.random() * 4 ); cards[x] = 1 + ( int ) ( Math.random() * 13 ); if ( y == cardSuit && cards[x] == cardNumber ) { //y = 1 + ( int ) ( Math.random() * 4 ); //cards[x] = 1 + ( int ) ( Math.random() * 13 ); } System.out.print( cards[x] + "-" + y + " " ); } System.out.println(); System.out.println(); } } }
[ November 14, 2004: Message edited by: Kenshin Himura ]

You know..sometimes my head just does not work for programming. Thanks for all your help guys, I got it working. Layne cleared up what the others where trying to get through my thick head hehe . Here's the code if your interested.

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Review2B extends JApplet { int x,y; public void init() { for ( int y = 6; y > 1; y-- ) { for ( int x = 1; x < y; x++ ) { System.out.print( "*" ); } System.out.println(); } } }

Yes..But isn't that what I did in my code? Switched the x and th y around?