# Thread: Pascal Triangle help

1. Member Join Date
May 2008
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## Pascal Triangle help

hey everyone i am new to Java that's why i need any help i can get.
i need to fill up the function Rows returns ragged array containing the first n rows of Pascal's triangle.
i tried playing around with it but considering i am totally new to this i have no idea if i am doing it right or how it should be implemented. I think i am doing way too much of what needs to be done.

can someone please take a look and based on what's given in the main function right now tell me what Rows should look like...

Java Code:
```public class Pascal {
public static int[][] Rows(int n){
int[][] pt = new int[n][];
for (int i = 0; i < n; i++) {
pt[i] = new int[i + 1];                            // Construct row i.
pt[i] = 1;                              // Leftmost value of row i.
for (int j = 1; j < i; j++) {
pt[i][j] = pt[i - 1][j - 1] + pt[i - 1][j];  // Sum 2 entries above.
}
pt[i][i] = 1;                             // Rightmost value of row i.
}
return pt;
}

public static void main(String[] args) {
if (args.length != 1) {
System.out.println("usage: java " + Pascal.class.getName() + " rows");
System.exit(1);
}
int n = Integer.parseInt(args);
if (n > 0) {
int[][] pascal = Rows(n);
for (int[] row : pascal) {
for (int v : row) System.out.print(v + " ");
System.out.println("");
}
}
}
}```

when i try running this of course nothing gets printed except the usage:java message.

thanks a lot :)  Reply With Quote

2. ## I would use recursion to generate the Fibonacci numbers then just print them out.  Reply With Quote

3. Member Join Date
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##  Originally Posted by Zosden I would use recursion to generate the Fibonacci numbers then just print them out.
thanks for response... but would you mind actually showing me how it should be done.. i am clueless oh that part :confused:
Main function stays as it is other functions is the one that needs modification...

thanks.  Reply With Quote

4. ## Heres a nice template for recursion

Java Code:
```public <modifier> recusiveAlg(You need some sort of parameter)
{
if(some sort of stopping criteria)
{
return something;
}
else
{
return recursiveAlg(your parameter - 1)
}
}```
Try to do this with Fibonacci numbers

hint: Fibonacci's numbers are the previous fib number + the one before the pervious fib number.  Reply With Quote

5. Member Join Date
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##  Originally Posted by Zosden Heres a nice template for recursion

Java Code:
```public <modifier> recusiveAlg(You need some sort of parameter)
{
if(some sort of stopping criteria)
{
return something;
}
else
{
return recursiveAlg(your parameter - 1)
}
}```
Try to do this with Fibonacci numbers

hint: Fibonacci's numbers are the previous fib number + the one before the pervious fib number.
hmmm correct me if i'm wrong but isn't it already implemented in the main function?

Java Code:
```if (n > 0) {
int[][] pascal = Rows(n);
for (int[] row : pascal) {
for (int v : row) System.out.print(v + " ");
System.out.println("");```
all Rows has to do is to generate the array somehow to decide the row number...
Last edited by Magic101; 05-01-2008 at 07:58 PM.  Reply With Quote

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