Fibonacci Number modulo M

FibonacciHuge.java

import java.math.BigInteger;
import java.util.*;

public class FibonacciHuge {
  public static long getFibonacciHugeNaive(long n, long m) {
    if (n <= 1) return n;

    BigInteger previous = BigInteger.ZERO;
    BigInteger current = BigInteger.ONE;

    for (long i = 0; i < n - 1; ++i) {
      BigInteger tmpPrevious = previous;
      previous = current;
      current = tmpPrevious.add(current);
    }

    return current.mod(BigInteger.valueOf(m)).longValue();
  }

  public static long getFibonacciHugeFast(long n, long m) {
    long pisanoNo = getPisanoPeriod(m);

    n = pisanoNo > 0 ? n % pisanoNo : n;

    return getFibonacci(n).mod(BigInteger.valueOf(m)).longValue();
  }

  public static long getPisanoPeriod(long m) {
    long prev = 0;
    long curr = 1;
    long res = 0;

    for (long i = 0; i < m * m; i++) {
      long temp = curr;
      curr = (prev + curr) % m;
      prev = temp;

      if (prev == 0 && curr == 1) {
        return i + 1;
      }
    }

    return res;
  }

  private static BigInteger getFibonacci(long n) {
    if (n <= 1) {
      return BigInteger.valueOf(n);
    }

    BigInteger prev = BigInteger.ZERO;
    BigInteger curr = BigInteger.ONE;

    for (int i = 2; i <= n; i++) {
      BigInteger temp = curr;
      curr = prev.add(curr);
      prev = temp;
    }

    return curr;
  }

  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    long n = scanner.nextLong();
    long m = scanner.nextLong();
    System.out.println(getFibonacciHugeFast(n, m));
  }
}