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ExtendedEuclideanAlgorithmImpl.java
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ExtendedEuclideanAlgorithmImpl.java
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package extended_euclidean_algorithm;
import extended_euclidean_algorithm.extended_eucliden_formula.EEAFormula;
import extended_euclidean_algorithm.extended_eucliden_formula.EEAFormulaImpl;
import java.math.BigInteger;
/**
* Extended Euclidean Algorithm implementation
*/
public class ExtendedEuclideanAlgorithmImpl implements ExtendedEuclideanAlgorithm{
private EEAFormula prevFormula;
private EEAFormula prevPrevFormula;
@Override
public void calculateExtendedEuclideanAlgorithm(BigInteger r0, BigInteger r1){
BigInteger s0 = BigInteger.valueOf(1);
BigInteger s1 = BigInteger.valueOf(0);
BigInteger t0 = BigInteger.valueOf(0);
BigInteger t1 = BigInteger.valueOf(1);
BigInteger original_r0 = r0;
BigInteger original_r1 = r1;
prevFormula = new EEAFormulaImpl(s1, r0, t1, r1);
prevPrevFormula = new EEAFormulaImpl(s0, r0, t0, r1);
BigInteger remainder = r0.remainder(r1);
BigInteger quotient = r0.divide(r1);
while (remainder.compareTo(BigInteger.ZERO) != 0){
BigInteger newCoefficient_s = prevPrevFormula.getCoefficient_s().subtract(quotient.multiply(prevFormula.getCoefficient_s()));
BigInteger newCoefficient_t = prevPrevFormula.getCoefficient_t().subtract(quotient.multiply(prevFormula.getCoefficient_t()));
prevPrevFormula = prevFormula;
prevFormula = new EEAFormulaImpl(newCoefficient_s, original_r0, newCoefficient_t, original_r1);
BigInteger newRemainder = r1.remainder(remainder);
quotient = r1.divide(remainder);
r1 = remainder;
remainder = newRemainder;
}
}
/**
* After running method calculateExtendedEuclideanAlgorithm(BigInteger r0, BigInteger r1)
* invoke this method to see extended euclidean formula in a string format.
* @return
*/
@Override
public String getEuclideanAlgorithmInString(){
return this.prevFormula.toString();
}
/**
* After running method calculateExtendedEuclideanAlgorithm(BigInteger r0, BigInteger r1)
* invoke this method to see formula result which is gcd
* @return
*/
@Override
public BigInteger getExtendedEuclideanFormulaResult(){
return this.prevFormula.getExtendedEuclideanFormulaResult();
}
@Override
public BigInteger getCoefficientOfR0() {
return prevFormula.getCoefficient_s();
}
@Override
public BigInteger getCoefficientOfR1() {
return prevFormula.getCoefficient_t();
}
}