1.
1 package algorithms.analysis14; 2 3 import algorithms.util.StdOut; 4 import algorithms.util.StdRandom; 5 6 /****************************************************************************** 7 * Compilation: javac DoublingTest.java 8 * Execution: java DoublingTest 9 * Dependencies: ThreeSum.java Stopwatch.java StdRandom.java StdOut.java 10 * 11 * % java DoublingTest 12 * 250 0.0 13 * 500 0.0 14 * 1000 0.1 15 * 2000 0.6 16 * 4000 4.5 17 * 8000 35.7 18 * ... 19 * 20 ******************************************************************************/ 21 22 /** 23 * The <tt>DoublingTest</tt> class provides a client for measuring 24 * the running time of a method using a doubling test. 25 * <p> 26 * For additional documentation, see <a href="http://algs4.cs.princeton.edu/14analysis">Section 1.4</a> 27 * of <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne. 28 * 29 * @author Robert Sedgewick 30 * @author Kevin Wayne 31 */ 32 public class DoublingTest { 33 private static final int MAXIMUM_INTEGER = 1000000; 34 35 // This class should not be instantiated. 36 private DoublingTest() { } 37 38 /** 39 * Returns the amount of time to call <tt>ThreeSum.count()</tt> with <em>N</em> 40 * random 6-digit integers. 41 * @param N the number of integers 42 * @return amount of time (in seconds) to call <tt>ThreeSum.count()</tt> 43 * with <em>N</em> random 6-digit integers 44 */ 45 public static double timeTrial(int N) { 46 int[] a = new int[N]; 47 for (int i = 0; i < N; i++) { 48 a[i] = StdRandom.uniform(-MAXIMUM_INTEGER, MAXIMUM_INTEGER); 49 } 50 Stopwatch timer = new Stopwatch(); 51 ThreeSum.count(a); 52 return timer.elapsedTime(); 53 } 54 55 /** 56 * Prints table of running times to call <tt>ThreeSum.count()</tt> 57 * for arrays of size 250, 500, 1000, 2000, and so forth. 58 */ 59 public static void main(String[] args) { 60 for (int N = 250; true; N += N) { 61 double time = timeTrial(N); 62 StdOut.printf("%7d %5.1f ", N, time); 63 } 64 } 65 }
2.
1 package algorithms.analysis14; 2 3 import algorithms.util.StdOut; 4 import algorithms.util.StdRandom; 5 6 /****************************************************************************** 7 * Compilation: javac DoublingRatio.java 8 * Execution: java DoublingRatio 9 * Dependencies: ThreeSum.java Stopwatch.java StdRandom.java StdOut.java 10 * 11 * 12 * % java DoublingRatio 13 * 250 0.0 2.7 14 * 500 0.0 4.8 15 * 1000 0.1 6.9 16 * 2000 0.6 7.7 17 * 4000 4.5 8.0 18 * 8000 35.7 8.0 19 * ... 20 * 21 ******************************************************************************/ 22 23 /** 24 * The <tt>DoublingRatio</tt> class provides a client for measuring 25 * the running time of a method using a doubling ratio test. 26 * <p> 27 * For additional documentation, see <a href="http://algs4.cs.princeton.edu/14analysis">Section 1.4</a> 28 * of <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne. 29 * 30 * @author Robert Sedgewick 31 * @author Kevin Wayne 32 */ 33 public class DoublingRatio { 34 private static final int MAXIMUM_INTEGER = 1000000; 35 36 // This class should not be instantiated. 37 private DoublingRatio() { } 38 39 /** 40 * Returns the amount of time to call <tt>ThreeSum.count()</tt> with <em>N</em> 41 * random 6-digit integers. 42 * @param N the number of integers 43 * @return amount of time (in seconds) to call <tt>ThreeSum.count()</tt> 44 * with <em>N</em> random 6-digit integers 45 */ 46 public static double timeTrial(int N) { 47 int[] a = new int[N]; 48 for (int i = 0; i < N; i++) { 49 a[i] = StdRandom.uniform(-MAXIMUM_INTEGER, MAXIMUM_INTEGER); 50 } 51 Stopwatch timer = new Stopwatch(); 52 ThreeSum.count(a); 53 return timer.elapsedTime(); 54 } 55 56 /** 57 * Prints table of running times to call <tt>ThreeSum.count()</tt> 58 * for arrays of size 250, 500, 1000, 2000, and so forth, along 59 * with ratios of running times between successive array sizes. 60 */ 61 public static void main(String[] args) { 62 double prev = timeTrial(125); 63 for (int N = 250; true; N += N) { 64 double time = timeTrial(N); 65 StdOut.printf("%6d %7.1f %5.1f ", N, time, time/prev); 66 prev = time; 67 } 68 } 69 }