Code clean-up

Author: phishman3579

src/com/jwetherell/algorithms/mathematics/DiscreteLogarithm.java

@@ -5,61 +5,64 @@
 import static java.lang.Math.sqrt;
 
 /**
- * https://en.wikipedia.org/wiki/Discrete_logarithm
- * a^x = b mod p
- * x = ?
+ * In mathematics, a discrete logarithm is an integer k exponent solving the equation bk = g, where b and g are 
+ * elements of a group. Discrete logarithms are thus the group-theoretic analogue of ordinary logarithms, which 
+ * solve the same equation for real numbers b and g, where b is the base of the logarithm and g is the value whose 
+ * logarithm is being taken.
+ * <p>
+ * @see <a href="https://en.wikipedia.org/wiki/Discrete_logarithm">Discrete Logarithm (Wikipedia)</a>
  * <br>
- * Created on 03.07.2017.
- *
- * @author lucjanroslanowski
+ * @author Lucjan Rosłanowski <[email protected]>
+ * @author Justin Wetherell <[email protected]>
  */
 public class DiscreteLogarithm {
-    private static long NO_SOLUTION = -1;
-    private HashMap<Long, Long> set = new HashMap<>();
+
+    public static final long NO_SOLUTION = -1;
+
+    private final HashMap<Long, Long> set = new HashMap<Long, Long>();
 
     private long pow(long a, long x, long p) {
-        if (x == 0) {
+        if (x == 0)
             return 1;
-        }
 
-        if (x == 1) {
+        if (x == 1)
             return a % p;
-        }
 
-        if (x % 2 != 0) {
+        if (x % 2 != 0)
             return (a * pow(a, x - 1, p)) % p;
-        } else {
-            long temp = pow(a, x / 2, p) % p;
-            return (temp * temp) % p;
-        }
-    }
 
+        final long temp = pow(a, x / 2, p) % p;
+        return (temp * temp) % p;
+    }
 
     private long getDiscreteLogarithm(long s, long a, long p) {
         for (long i = 0; i < s; ++i) {
             long el = pow(a, (i * s) % p, p);
             el = pow(el, p - 2, p);
 
-            if (set.containsKey(el)) {
+            if (set.containsKey(el))
                 return i * s + set.get(el);
-            }
         }
         return NO_SOLUTION;
     }
 
     private void generateSet(long a, long b_1, long p, long s) {
         for (long i = 0; i < s; ++i) {
-            long first = (pow(a, i, p) * b_1) % p;
-            if (!set.containsKey(first)) {
+            final long first = (pow(a, i, p) * b_1) % p;
+            if (!set.containsKey(first))
                 set.put(first, i);
-            }
         }
     }
 
+    /**
+     * Returns DiscreteLogarithm.NO_SOLUTION when a solution cannot be found
+     */
     public long countDiscreteLogarithm(final long a, final long b, final long p) {
-        long s = (long) sqrt(p) + 1;
-        long b_1 = pow(b, p - 2, p);
+        final long s = (long) sqrt(p) + 1;
+        final long b_1 = pow(b, p - 2, p);
+        set.clear();
+
         generateSet(a, b_1, p, s);
         return getDiscreteLogarithm(s,a,p);
     }
-}
+}

test/com/jwetherell/algorithms/mathematics/DiscreteLogarithmTest.java renamed to test/com/jwetherell/algorithms/mathematics/test/DiscreteLogarithmTest.java

@@ -1,15 +1,11 @@
-package com.jwetherell.algorithms.mathematics;
+package com.jwetherell.algorithms.mathematics.test;
 
 import org.junit.Test;
 
+import com.jwetherell.algorithms.mathematics.DiscreteLogarithm;
+
 import static org.junit.Assert.assertTrue;
 
-/**
- * <br>
- * Created on 04.07.2017.
- *
- * @author lucjanroslanowski
- */
 public class DiscreteLogarithmTest {
 
     @Test