Print the Fibonacci sequence - Programmers Heaven

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# Print the Fibonacci sequence

Posts: 10Member
hi,i want to print out the fibonacci sequence:
1 1 2 3 5 8....
i know how to get the nth number in the sequence, but i stuck at
where to addin the println setence, here is my code:

public class Fibonacci
{
public Fibonacci()
{
}

public static void main(int n)
{
System.out.println("The nth Fibonacci number show as following: ");
recusion(n);
}

private int recusion(int n)
{
if (n==0 || n==1)
{
return 1;
}
else
{
int sum = recusion(n-1) + recusion(n-2);
System.out.print(sum + " ");
return sum;
}
}
}

• Posts: 684Member
After you grab the return value, just stick it in the SOP in main.

Unless you have to use recursion, I would avoid it for fibonacci type problems. It is a good example of recursion and a good example of when not to use it. An iterative version is much faster, due to not having a ton of methods being placed on the call stack.

: hi,i want to print out the fibonacci sequence:
: 1 1 2 3 5 8....
: i know how to get the nth number in the sequence, but i stuck at
: where to addin the println setence, here is my code:
:
: public class Fibonacci
: {
: public Fibonacci()
: {
: }
:
: public static void main(int n)
: {
: System.out.println("The nth Fibonacci number show as following: ");
: recusion(n);
: }
:
: private int recusion(int n)
: {
: if (n==0 || n==1)
: {
: return 1;
: }
: else
: {
: int sum = recusion(n-1) + recusion(n-2);
: System.out.print(sum + " ");
: return sum;
: }
: }
: }
:
:

• Posts: 147Member
hi,
don't use a recursive fibonacci function since it is very inefficient.
try this:

[code]
/**
* the recursive fibonacci function
*
* @param n
* saves the index of the fibonacci number to compute
* @return the Nth fibonacci number
*/
private static long f(int n) {
if ((n == 0) || (n == 1)) {
return 1;
}
return f(n - 2) + f(n - 1);
}

/**
* computes the Nth fibonacci number. BE CAREFULL! This method does no range
* checking! It may return incorrect results if the result is larger than
*
* @param n
* the index of the fibonacci number
* @param recursive
* indicates whether to compute the fibonacci numbers recursive
* or iterative
*
* @return the Nth fibonacci number
*/
public static long fibonacci(int n, boolean recursive) {
if (n < 0) {
throw new IllegalArgumentException("no negative numbers allowed");
}
if ((n == 0) || (n == 1)) {
return 1;
}

if (recursive) {
return f(n);
}

long current = 1;
long pred = 1;
long result = pred + current;

for (int i = 2; i < n; i++) {
pred = current;
current = result;
result = pred + current;
}

return result;
}

/**
* print out the numbers...
*/
public static void main(String[] args) {
int n = 43;

long start = System.currentTimeMillis();
long result = fibonacci(n, true);
long stop = System.currentTimeMillis();

System.out.println("<<iterative>> fib("+n+") = "+result+" [computed in "+(stop-start)+" ms]");

start = System.currentTimeMillis();
result = fibonacci(n, false);
stop = System.currentTimeMillis();

System.out.println("<<recursive>> fib("+n+") = "+result+" [computed in "+(stop-start)+" ms]");
}
[/code]
• Posts: 67Member