我的算法没有正常工作 - Diophantic线性方程

Question

这段代码试图解决Diophantics线性方程，这个方程的形式是Ax + By = C. 这个班有两个属性＆＃34; a＆＃34;和＆＃34; b＆＃34;，并且构造必须接收此数字

public class LongPair {

    private long a, b;  // the pair of longs

    public LongPair(long aIn, long bIn) {
        a = aIn;
        b = bIn;
    }

    public LongPair() {
        a = 0;
        b = 0;
    }

    public long getFirst() {
        return a;
    }

    public long getSecond() {
        return b;
    }

    public void setFirst(long aIn) {
        a = aIn;
    }

    public void setSecond(long bIn) {
        b = bIn;
    }

    // Compute the greatest common divisor of to integers r and s.
    // Either may be positive, negative, or zero.  For negative numbers,
    // the GCD is that if their absolute values, that is, 
    //      GCD(r,s) = GCD(|r|,|s|).
    // For zero,  GCD(r,0) = r, and  GCD(0,0) = 0.
    // The Euclidean algorithm is used to compute the GCD.
    public static long GCD(long r, long s) {
        if (r == 0) {
            return s;
        }
        if (s == 0) {
            return r;
        }
        if (r < 0) {
            r = -r;
        }
        if (s < 0) {
            s = -s;
        }
        if (r > s) {
            return GCD(r % s, s);
        } else {
            return GCD(r, s % r);
        }
    } // GCD

    // Compute the least common multiple of two integers
    public static long LCM(long r, long s) {
        if (r == 0 || s == 0) {
            return 0;
        }
        return (r / GCD(r, s)) * s;
    } // LCM

    // Return the greatest common divisor of the pair of numbers
    public long GCD() {
        return GCD(a, b);
    }

    // Return the least common multiple of the pair of numbers
    public long LCM() {
        return LCM(a, b);
    }

    // Find a solution to the linear Diophantine equation
    //     ax + by = c
    // If GCD(a,b) does not divide c, then an ArithmeticException is thrown
    public static LongPair linearDiophantine(long a, long b, long c)
            throws ArithmeticException {
        if (c == 0) {        // then a solution to  ax + by = 0  is  x = 0, y = 0.
            return new LongPair(0, 0);
        } else if (a == 0) { // then a solution to  0x + by = c  is  x = 0, y = c/b.
            if (b == 0 || c % b != 0) {
                throw new ArithmeticException("No solution to the linear Diophantine equation " + a + "x + " + b + "y = " + c);
            } else {
                return new LongPair(0, c / b);
            }
        } else if (b == 0) { // then a solution to  ax + 0y = c  is  x = c/a, y = 0.
            if (c % a != 0) {
                throw new ArithmeticException("No solution to the linear Diophantine equation " + a + "x + " + b + "y = " + c);
            } else {
                return new LongPair(c / a, 0);
            }
        } else if (c % GCD(a, b) != 0) {
            throw new ArithmeticException("No solution to the linear Diophantine equation " + a + "x + " + b + "y = " + c);
        } // else there is a solution 
        // work with positive numbers
        long d = Math.abs(a);
        long e = Math.abs(b);
        long x, y;
        if (d <= e) { // Divide d into e with quotient q and remainder r
            long q = e / d;   // so that e = qd + r.
            long r = e % d;   // Then a solution to the equation  dx + ey = c  is  x = z-q where
            // the pair y, z is a solution to the equation  dz + ry = c
            LongPair solution = linearDiophantine(d, r, c);
            x = solution.getFirst() - q;
            y = solution.getSecond();
        } else {     // d>e
            long q = d / e;
            long r = d % e;   // d = qe + r.
            LongPair solution = linearDiophantine(r, e, c);
            x = solution.getFirst();
            y = solution.getSecond() - q ;
        } // if/else  
        // take care of the signs
        if (a < 0) {
            x = -x;
        }
        if (b < 0) {
            y = -y;
        }
        return new LongPair(x, y);
    } // linearDiophantine  

    // Solve the linear Diophantine equation where the coefficients are this pair
    // of numbers
    public LongPair linearDiophantine(long c) {
        return linearDiophantine(a, b, c);
    }

    public static void main(String[] args) {

        LongPair lpn = new LongPair(8, 20);
        LongPair solucion = lpn.linearDiophantine(120);
        System.out.println("x = " + solucion.getFirst());
        System.out.println("y = "+ solucion.getSecond());

    }
}

算法中出现了错误