Android Open Source - EulerSolutions Even Fibonacci Nm Calculator

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License

The source code is released under:

MIT License

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Java Source Code

package com.eulersolutions.model;
/*from  w w  w  .  jav a2  s.  c o  m*/
import java.util.ArrayList;
import java.util.List;

import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;

public class EvenFibonacciNmCalculator extends ProblemCalculator {
  
  private static final String TAG = "EulerSolutions-EvenFibNmCalc";

  public EvenFibonacciNmCalculator()
  {
    super();
  }
  
  public EvenFibonacciNmCalculator(Parcel source)
  {
    super(source);
  }
  
  @Override
  protected boolean validInput(List<Number> values) {
    Log.i(TAG, "entered Valid Input");
    if(values == null || values.size() != 1)
    {
      return false;
    }
    
    if(values.get(0).longValue() <= 0)
    {
      return false;
    }
    return true;
  }

  @Override
  protected List<Number> parseInput(List<String> values) {
    Log.i(TAG, "entered parse input");
    ArrayList<Number> toReturn = new ArrayList<Number>();
    
    if(values.size() != 1)
    {
      return null;
    }
    
    try
    {
      toReturn.add(Long.parseLong(values.get(0)));
    }
    catch(NumberFormatException error)
    {
      return null;
    }
    
    return toReturn;
  }

  @Override
  protected Number calculate(List<Number> values) {
    Log.i(TAG, "entered Calculate");
    Long toReturn = Long.valueOf(0);
    long maxValue = (Long) values.get(0);
    long sum = 0;
    int currentFibSequence = 0;
    long currentFibNm = 0;
    
    if(maxValue == 1)
    {
      toReturn = Long.valueOf(0);
    }
    else if(maxValue <= 8)
    {
      toReturn = Long.valueOf(2);
    }
    else
    {
      currentFibNm = 2;
      sum = 0;
      currentFibSequence = 3;
      while(currentFibNm < maxValue)
      {
        sum = sum + currentFibNm;
        currentFibSequence = currentFibSequence + 3;
        currentFibNm = calculateNFibNm(currentFibSequence);
      }
      toReturn = Long.valueOf(sum);
    }
    return toReturn;
  }
  
  private long calculateNFibNm(int sequenceNm)
  {
    Log.i(TAG, "entered CalculateNFibNm");
    double firstComponent = 0;
    double secondComponent = 0;
    double tempInternal = 0;
    double constant = (1/Math.sqrt(5));
    
    tempInternal = (1 + Math.sqrt(5))/2;
    firstComponent = Math.pow(tempInternal, sequenceNm);
    
    tempInternal = (1 - Math.sqrt(5))/2;
    secondComponent = Math.pow(tempInternal, sequenceNm);
    
    return (long) ((firstComponent - secondComponent) * constant);
  }
  
  public static final Parcelable.Creator<EvenFibonacciNmCalculator> CREATOR = 
      new Parcelable.Creator<EvenFibonacciNmCalculator>() {
    public EvenFibonacciNmCalculator createFromParcel(Parcel in) {
      return new EvenFibonacciNmCalculator(in);
    }

    public EvenFibonacciNmCalculator[] newArray(int size) {
      return new EvenFibonacciNmCalculator[size];
    }
  };
}

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