fibonnacci

/**
 * Fibonacci Sequence
 * <pre>
 * <b>History:</b>
 *    2018.06.11, 0.1, KIM TAE HO
 * </pre>
 *
 * @author 　KIM TAE HO
 * @version 0.1, 2018.06.11
 * @see    None
 */
import java.util.HashMap;
import java.util.Map;
import java.math.BigInteger;

public class Fibonacci {

    private static Map<Integer, BigInteger> cacheOfSum = new HashMap<>();
public static void main(String[] args)
{

int needNumber = 8181;

cacheOfSum.put(0, BigInteger.ZERO);
cacheOfSum.put(1, BigInteger.ONE);

        System.out.println(getFibonacci(needNumber));

}

    /**
     * (Fibonacci Logic)
     * @param sequenceNumber Atom of fibonacci more then 0   
     * @return  Sum Number with preview Number
     */

private static BigInteger getFibonacci(int sequenceNumber)
{
    if (cacheOfSum.containsKey(sequenceNumber))
    {
        return cacheOfSum.get(sequenceNumber);
    }
   
        return recursiveCachedSum(sequenceNumber);
}

    /**
     * Cached Value Of specipied serquence Number that fibonacci
     * @param sequenceNumber of using memoization
     * @return  Sum Number with preview Number
     */
private static BigInteger recursiveCachedSum(int sequenceNumber)
{
   
    BigInteger calcSum = getFibonacci(sequenceNumber - 2).add(getFibonacci(sequenceNumber - 1));
    cacheOfSum.put(sequenceNumber, calcSum);
   
    return calcSum;
}
}