DoublingTest.java
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/******************************************************************************
* Compilation: javac DoublingTest.java
* Execution: java DoublingTest
* Dependencies: ThreeSum.java Stopwatch.java StdRandom.java StdOut.java
*
* % java DoublingTest
* 250 0.0
* 500 0.0
* 1000 0.1
* 2000 0.6
* 4000 4.5
* 8000 35.7
* ...
*
******************************************************************************/
package edu.princeton.cs.algs4;
/**
* The {@code DoublingTest} class provides a client for measuring
* the running time of a method using a doubling test.
* <p>
* For additional documentation, see <a href="http://algs4.cs.princeton.edu/14analysis">Section 1.4</a>
* of <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public class DoublingTest {
private static final int MAXIMUM_INTEGER = 1000000;
// This class should not be instantiated.
private DoublingTest() { }
/**
* Returns the amount of time to call {@code ThreeSum.count()} with <em>n</em>
* random 6-digit integers.
* @param n the number of integers
* @return amount of time (in seconds) to call {@code ThreeSum.count()}
* with <em>n</em> random 6-digit integers
*/
public static double timeTrial(int n) {
int[] a = new int[n];
for (int i = 0; i < n; i++) {
a[i] = StdRandom.uniform(-MAXIMUM_INTEGER, MAXIMUM_INTEGER);
}
Stopwatch timer = new Stopwatch();
ThreeSum.count(a);
return timer.elapsedTime();
}
/**
* Prints table of running times to call {@code ThreeSum.count()}
* for arrays of size 250, 500, 1000, 2000, and so forth.
*
* @param args the command-line arguments
*/
public static void main(String[] args) {
for (int n = 250; true; n += n) {
double time = timeTrial(n);
StdOut.printf("%7d %5.1f\n", n, time);
}
}
}
/******************************************************************************
* Copyright 2002-2016, Robert Sedgewick and Kevin Wayne.
*
* This file is part of algs4.jar, which accompanies the textbook
*
* Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
* Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
* http://algs4.cs.princeton.edu
*
*
* algs4.jar is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* algs4.jar is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with algs4.jar. If not, see http://www.gnu.org/licenses.
******************************************************************************/