Wednesday, January 4, 2012

Write a Java code snippet to calculate the sum of the first 100 numbers in the Fibonacci sequence

Write a Java code snippet to calculate the sum of the first 100 numbers in the Fibonacci sequence

Fibonnaci numbers follow this rule:
  • F(0) = 0;
  • F(1) = 1;
  • F(n) = F(n-1) + F(n-2), n ≥ 2, n is integer
The first 10 numbers in the Fibonacci sequence are: 0, 1, 1*, 2, 3, 5, 8, 13, 21 and 34. Note that the number 1 appears twice in the sequence, by definition.

Here is my Java code snipet (as image and as text, so you can copy):

/** © 2012 interviewqa4java.blogspot.com*/
package iqa4java;

 public class Fibonacci {

    /**
     * Write a Java code snippet to calculate the sum of the first 100 numbers in the
     * Fibonacci sequence.
     */
    public static void main(String[] args) {
      
        System.out.println("Sum of the first 100 numbers in the Fibonacci sequence= "
                +getFibonacciSum(100));
    }
  
    public static long getFibonacciSum(int sequenceSize){
        long sum, fb0=0, fb1=1, fb2;
        sum=fb0+fb1;
      
        for (int i = 2; i < sequenceSize; i++) {
          
            fb2= fb1 + fb0;
            sum+=fb2;
          
            fb0=fb1;      
            fb1=fb2;
        }
        return sum;
    }
}


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