Gets the Fibonacci number at position n in the Fibonacci Sequence. - Java java.lang

Java examples for java.lang:Math Geometry Shape

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Description

Gets the Fibonacci number at position n in the Fibonacci Sequence.

Demo Code

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public class Main{
    /**
     * Gets the Fibonacci number at position n in the Fibonacci Sequence.
     *
     * @param n an integer value indicating the nth number in the Fibonacci Sequence.
     * @return the nth number in the Fibonacci Sequence.
     * @throws IllegalArgumentException if the position (n) is less than 1.
     * @see #fibonacciSequence(int)
     */
    public static int fibonacciNumber(final int n) {
        return fibonacciSequence(n)[n - 1];
    }
    /**
     * Calculates the Fibonacci Sequence to the nth position.
     *
     * @param n an integer value indicating the position of the nth element in the Fibonacci Sequence.
     * @return an integer array containing n elements of the Fibonacci Sequence.
     * @throws IllegalArgumentException if the position (n) is less than 1.
     */
    public static int[] fibonacciSequence(final int n) {
        Assert.argument(
                n > 0,
                "The number of elements from the Fibonacci Sequence to calculate must be greater than equal to 0!");

        int[] fibonacciNumbers = new int[n];

        for (int position = 0; position < n; position++) {
            if (position == 0) {
                fibonacciNumbers[position] = 0;
            } else if (position < 2) {
                fibonacciNumbers[position] = 1;
            } else {
                fibonacciNumbers[position] = (fibonacciNumbers[position - 1] + fibonacciNumbers[position - 2]);
            }
        }

        return fibonacciNumbers;
    }
}

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