JavaMath SolutionsRecursion

Write a method that takes a single int parameter and returns that element of the Fibonacci series.

The following Java coding solution is the first in a series of solutions for common recursion programming problems. It is perhaps not the best solution, and certainly not the only solution. If you’ve got a better idea, please share.

Problem:

The Fibonacci series: 0, 1, 1, 2, 3, 5, 8, 13, 21, has as its first 2 values, 0 and 1; each successive value if then calculated as the sum of the previous two values.

The first element in the series is the 0’th element, thus the value 8 is element 6 of the series.

The n’th element of the series, written as fib(n), is thus defined as:

  • n if n = 0 or n = 1
  • fib(n-1) + fib(n-2)

Write the int-valued method fib, that takes a single int parameter (say n), and recursively calculates and then returns the n’th element of the Fibonacci series.

public int fib(int n) {
	int sum;
	if (n==1) {
		return n;
	} else if (n==0) {
		return n;
	} else {
		return fib(n-1)+ fib(n-2);
	}
						 
}

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