Added the set method to Permutation

Author: cicirello

lib/jpt1.jar

@@ -36,7 +36,7 @@
  * manipulate permutations in a variety of ways.
  * 
  * @author <a href=https://www.cicirello.org/ target=_top>Vincent A. Cicirello</a>, <a href=https://www.cicirello.org/ target=_top>https://www.cicirello.org/</a> 
- * @version 1.19.5.9
+ * @version 1.19.5.10
  * @since 1.0
  */
 public final class Permutation implements Serializable, Iterable<Permutation>
@@ -505,13 +505,37 @@ public void removeAndInsert(int i, int size, int j) {
 		}
 	}
 
+	/**
+	 * Changes the state of this permutation to be identical to the elements of an array.
+	 *
+	 * @param p An array of integers. Each of the integers in the interval [0, p.length) 
+	 * must occur exactly one time each.
+	 * @throws IllegalArgumentException if p either contains duplicates, or contains any negative elements, 
+	 *         or contains any elements equal or greater than p.length.
+	 * @since 1.2.5
+	 */
+	public void set(int[] p) {
+		if (p.length != permutation.length) {
+			throw new IllegalArgumentException("Length of array must be same as that of permutation.");
+		}
+		boolean[] inP = new boolean[p.length];
+		for (int e : p) {
+			if (e < 0 || e >= p.length) throw new IllegalArgumentException("Elements of p must be in interval [0, p.length)");
+			if (inP[e]) throw new IllegalArgumentException("Duplicate elements of p are not allowed.");
+			inP[e] = true;
+		}
+		for (int i = 0; i < p.length; i++) {
+			permutation[i] = p[i];
+		}
+	}
+	
 	/**
 	 * Returns an Iterator over all Permutations the length of this Permutation.  Iteration begins at this Permutation.
 	 * This Iterator does not iterate over the integers within the Permutation.
 	 * If you do need to iterate over all permutations of a given length, then this method is much more efficient than
 	 * using the {@link #Permutation(int,int)} constructor repeatedly incrementing the value passed for the second parameter.
 	 * 
-	 * @since 2.0
+	 * @since 1.2
 	 * @return an Iterator
 	 */
 	@Override

src/org/cicirello/permutations/Permutation.java

@@ -149,6 +149,17 @@ public void testPermutationConstructorFromArray() {
 		}
 	}
 
+	@Test
+	public void testPermutationSetFromArray() {
+		int[][] arrays = { { 0 }, { 1, 0 }, { 1, 0, 2 }, { 3, 1, 2, 0 } };
+		for (int[] a : arrays) {
+			Permutation p = new Permutation(a.length, 0);
+			p.set(a);
+			validatePermutation(p, a.length);
+			for (int i = 0; i < a.length; i++) assertEquals("elements should be in same order", a[i], p.get(i));
+		}
+	}
+	
 	@Test
 	public void testPermutationCopyConstructor() {
 		for (int n = 1; n <= 10; n++) {