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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.util;
+
+import org.apache.commons.math3.exception.MathIllegalArgumentException;
+import org.apache.commons.math3.random.RandomGenerator;
+
+import java.io.Serializable;
+
+/**
+ * A strategy of selecting random index between begin and end indices.
+ *
+ * @since 3.4
+ */
+public class RandomPivotingStrategy implements PivotingStrategyInterface, Serializable {
+
+ /** Serializable UID. */
+ private static final long serialVersionUID = 20140713L;
+
+ /** Random generator to use for selecting pivot. */
+ private final RandomGenerator random;
+
+ /**
+ * Simple constructor.
+ *
+ * @param random random generator to use for selecting pivot
+ */
+ public RandomPivotingStrategy(final RandomGenerator random) {
+ this.random = random;
+ }
+
+ /**
+ * {@inheritDoc} A uniform random pivot selection between begin and end indices
+ *
+ * @return The index corresponding to a random uniformly selected value between first and the
+ * last indices of the array slice
+ * @throws MathIllegalArgumentException when indices exceeds range
+ */
+ public int pivotIndex(final double[] work, final int begin, final int end)
+ throws MathIllegalArgumentException {
+ MathArrays.verifyValues(work, begin, end - begin);
+ return begin + random.nextInt(end - begin - 1);
+ }
+}