Merge pull request #77 from achaJackson/master

#20. Generating and Implementing a Power set with Java

maths/powerset/PowerSet.java

@@ -0,0 +1,30 @@
+import java.util.*;
+public class PowerSet {
+
+        public static <T> Set<Set<T>> powerSet( Set<T> set ) {
+            T[] element = (T[]) set.toArray();
+            final int SET_LENGTH = 1 << element.length;
+            Set<Set<T>> powerSet = new HashSet<>();
+            for( int binarySet = 0; binarySet < SET_LENGTH; binarySet++ ) {
+                Set<T> subset = new HashSet<>();
+                for( int bit = 0; bit < element.length; bit++ ) {
+                    int mask = 1 << bit;
+                    if( (binarySet & mask) != 0 ) {
+                        subset.add( element[bit] );
+                    }
+                }
+                powerSet.add( subset );
+            }
+            return powerSet;
+        }
+
+        public static void main(String[] args) {
+            Set<Character> test = new HashSet<>();
+            test.add( 'a' );
+            test.add( 'b' );
+            test.add( 'c' );
+            System.out.println("test = " + test);
+            Set<Set<Character>> result = powerSet( test );
+            System.out.println( result );
+        }
+    }