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tylerxian
How do I cheat?
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Joined: 18 Jan 2009
Posts: 4
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 Posted: Wed Mar 18, 2009 10:37 pm Post subject: Java Problem |
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Hello, sorry to impose on your time but can anyone help me write a short program from Java? I need to turn this program in to my teacher soon, but I don't really get Java.
I'm supposed to write a program that sums up all the integers between two numbers. Something like:
Enter starting number:20
Enter ending number:40
The sum from (starting number) to (ending number) is (the sums added in between ex. 20 +21 + 22... + 40)
Thank you.
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Frostbyt3
Master Cheater
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Joined: 07 Jan 2008
Posts: 323
Location: Australia
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| Posted: Wed Mar 18, 2009 11:02 pm Post subject: |
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If you know a bit of java, you can turn this into a working program pretty easily.
| Code: | int num = 20;
int i = 0;
int total = 0;
list<int> numToAdd = new list<int>();
static void Main(string[] args)
{
for(i = 0;i < 20; i++;)
{
int temp = i + 20;
numToAdd.Add(temp);
}
foreach(int n in numToAdd)
{
total += n;
}
System.Out.PrintIn(total.ToString());
} |
Never used java lists, might have to fix that up.
If it compiles after pasting, its a miracle!
Oh yes, you'll have to accept input, or if your afraid to do that, post back and I'll get it to accept command line arguments for the numbers.
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sloppy
Expert Cheater
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Posts: 123
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| Posted: Wed Mar 18, 2009 11:04 pm Post subject: |
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| Code: | int start = 20, end = 40, sum = 0;
for (int i = start; i <= end; i++)
{
sum += i;
} |
Been awhile since I've played with java, but the generic code above should do?
edit:
damn you frostbyt3 *shakes fist* 
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kitterz
Grandmaster Cheater Supreme
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Joined: 24 Dec 2007
Posts: 1268
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| Posted: Thu Mar 19, 2009 7:59 am Post subject: |
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int start = 20;
int end = 40;
//Using a arithmatic series forumla
double value = (end - start)((start + end)/2.0)
Edit: make a small mistake, here's the whole class
| Code: | //Using a arithmetic series formula
class test
{
public static void main (String[] args)
{
int start = 1;
int end = 5;
double value = ((end - start + 1) / 2.0) * (start + end);
System.out.println (value);
}
} |
Edit 2:
Yo let you know, the arithmetic series formula allows you to find the sum of a series of numbers.
Sn = (n/2)(N1 + Nn)
where Sn is the sum
where n is the number of terms
where N1 is the first number in the series
where Nn is the last number in the series.
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NoManchesPuto
I post too much
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Joined: 24 Jan 2009
Posts: 2820
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| Posted: Thu Mar 19, 2009 3:19 pm Post subject: java |
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| Sorry to bother yall, but can someone give me a download link for java so i may create projects and stuff?? plz and thx rep if it works.
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kitterz
Grandmaster Cheater Supreme
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Posts: 1268
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| Posted: Thu Mar 19, 2009 3:41 pm Post subject: Re: java |
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| Lord Dread wrote: | | Sorry to bother yall, but can someone give me a download link for java so i may create projects and stuff?? plz and thx rep if it works. |
downlaod eclipse's IDE. I find that it is very good.
DO NOT go for Ready To Program, as it has incomplete libraries and is crap. After all, they did go out of buisness.
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igoticecream
Grandmaster Cheater Supreme
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Joined: 23 Apr 2006
Posts: 1807
Location: 0x00400000
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| Posted: Thu Mar 19, 2009 4:52 pm Post subject: Re: java |
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| Code: |
import java.util.Scanner;
public class JHomeWork {
public static void main(String[] args) {
Scanner get = new Scanner(System.in);
int min = 0, max = 0;
try{
System.out.print("Min. number: ");
min = get.nextInt();
System.out.print("Max. number: ");
max = get.nextInt();
}
catch(Exception exc){
System.out.printf("Excepcion: %s\n",exc.toString());
}
finally{
for(int i = min; i != max+1; i++)
System.out.print(i + " - ");
}
}
} |
| kitterz wrote: | | Lord Dread wrote: | | Sorry to bother yall, but can someone give me a download link for java so i may create projects and stuff?? plz and thx rep if it works. |
downlaod eclipse's IDE. I find that it is very good.
DO NOT go for Ready To Program, as it has incomplete libraries and is crap. After all, they did go out of buisness. |
NetBeans is much better.
| Frostbyt3 wrote: | If you know a bit of java, you can turn this into a working program pretty easily.
| Code: | int num = 20;
int i = 0;
int total = 0;
list<int> numToAdd = new list<int>();
static void Main(string[] args)
{
for(i = 0;i < 20; i++;)
{
int temp = i + 20;
numToAdd.Add(temp);
}
foreach(int n in numToAdd)
{
total += n;
}
System.Out.PrintIn(total.ToString());
} |
Never used java lists, might have to fix that up.
If it compiles after pasting, its a miracle!
Oh yes, you'll have to accept input, or if your afraid to do that, post back and I'll get it to accept command line arguments for the numbers. |
Java is OOP... so if we want to work with java, lets work with OOP style, otherwise, use a structured programming. You code is C with Java stuff
Last edited by igoticecream on Thu Mar 19, 2009 4:59 pm; edited 1 time in total |
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Jani
Grandmaster Cheater
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Joined: 29 Dec 2006
Posts: 804
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| Posted: Thu Mar 19, 2009 4:58 pm Post subject: Re: java |
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| igoticecream wrote: | | kitterz wrote: | | downlaod eclipse's IDE. I find that it is very good. |
NetBeans is much better. |
They're both awful. Just get a good text editor and the compiler from Sun's site. For example, Notepad++ and JDK = way better than those IDEs.
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tylerxian
How do I cheat?
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Joined: 18 Jan 2009
Posts: 4
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| Posted: Thu Mar 19, 2009 5:05 pm Post subject: |
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| I really do appreciate the help! Thanks a lot guys!
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igoticecream
Grandmaster Cheater Supreme
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Posts: 1807
Location: 0x00400000
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| Posted: Thu Mar 19, 2009 5:09 pm Post subject: Re: java |
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| Jani wrote: | | igoticecream wrote: | | kitterz wrote: | | downlaod eclipse's IDE. I find that it is very good. |
NetBeans is much better. |
They're both awful. Just get a good text editor and the compiler from Sun's site. For example, Notepad++ and JDK = way better than those IDEs. |
Just no
You cannot compare developing with an IDE with delevoping with a text editor =S
Just a question: What do you do when your application do not work as you want? Do you debug? Then... How?
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tylerxian
How do I cheat?
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Joined: 18 Jan 2009
Posts: 4
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| Posted: Thu Mar 19, 2009 5:37 pm Post subject: |
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Sorry to bother you again, but there's a misunderstanding regarding the program, igoticecream's program is the closest to the output that I wanted. Maybe a better example would be better.
Ex.
Starting number: 20
Ending number: 40
The sum of the integers from 20 to 40 is 630.
I was amazed by the programs though, I could only read about 60% of it, maybe even less. (I might take more Java next year, I'm just a BASIC student right now.)
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igoticecream
Grandmaster Cheater Supreme
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Joined: 23 Apr 2006
Posts: 1807
Location: 0x00400000
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| Posted: Thu Mar 19, 2009 6:36 pm Post subject: |
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| Code: |
import java.util.Scanner;
public class JHomeWork {
public static void main(String[] args) {
Scanner get = new Scanner(System.in);
int min = 0, max = 0, holder = 0;
try{
System.out.print("Min. number: ");
min = get.nextInt();
System.out.print("Max. number: ");
max = get.nextInt();
}
catch(Exception exc){
System.out.printf("Excepcion: %s\n",exc.toString());
}
finally{
for(int i = min; i != max+1; i++){
holder += i;
}
System.out.print(holder);
}
}
}
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tylerxian
How do I cheat?
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Joined: 18 Jan 2009
Posts: 4
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| Posted: Fri Mar 20, 2009 12:25 am Post subject: |
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Thanks a lot for your help igoticecream! I'm such a beginner at Java, the best 'error-free' code I could come up with was
| Code: |
import apcslib.*;
import chn.util.*;
public class 1JAVA31
{
public static void main(String[] args)
{
ConsoleIO c = new ConsoleIO();
System.out.print("Enter the starting number:");
int sn = c.readInt();
System.out.print("Enter the ending number:");
int en = c.readInt();
int rn = sn + en;
System.out.println("The running sum between " + sn);
System.out.println("and " + en);
System.out.println("is" + rn);
}
}
|
Then, I was stumbled on what to do next, I guess that's what you get for taking only a few lessons on Java and the rest on BASIC. Anyways thanks a lot!
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Jani
Grandmaster Cheater
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Joined: 29 Dec 2006
Posts: 804
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| Posted: Fri Mar 20, 2009 3:57 am Post subject: Re: java |
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| igoticecream wrote: | Just no
You cannot compare developing with an IDE with delevoping with a text editor =S |
I was saying they're both awful IDEs.
| igoticecream wrote: | | Just a question: What do you do when your application do not work as you want? Do you debug? Then... How? |
jdb. How do you think ppl with for example gcc debug? You know, you can debug on command line too... It doesn't require an IDE with GUI.
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VolatileAce
Cheater
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Joined: 19 Mar 2009
Posts: 30
Location: 0001001100110111
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| Posted: Sat Mar 21, 2009 8:56 pm Post subject: |
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Another way to write it to run at O(1) time instead of O(n) time from looping through all the numbers would be something like this, notice I do not handle moronic errors that may be generated by the user:
| Code: | /**
* @(#)Tylerxian.java
*
*
* @author VolatileAce
* @version 1.00 2009/3/21
*/
import java.util.Scanner;
public class Tylerxian{
public static void main(String args[]){
Scanner in = new Scanner(System.in);
int x = 0, y = 0;
System.out.print("Please enter the starting number: ");
x = in.nextInt();
System.out.print("Please enter the ending number: ");
y = in.nextInt();
assert(x < y);
System.out.print("The sum of all the numbers inbetween(inclusive) is: " +
((y-x>>1<<1==y-x)?(y-x+1)*(x+y>>1):(y-x+1)*(x+y>>1)+((y+1-x)*(x+1+y>>1)-(y+1-x)*(x+y>>1)>>1)));
}
} |
What is being done here is that instead of adding up the number, I find the number in the middle of min and max by adding min with the subtraction of max and min. Then I multiply that number by the difference between min and max. Bitwise operations are used here to further increase efficiency of the code.
Hope this helps!
Last edited by VolatileAce on Sat Mar 21, 2009 10:44 pm; edited 1 time in total |
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