DoublingTest.java

Below is the syntax highlighted version of DoublingTest.java from §1.4 Analysis of Algorithms.

/*************************************************************************
 *  Compilation:  javac DoublingTest.java
 *  Execution:    java DoublingTest
 *  Dependencies: ThreeSum.java Stopwatch.java StdRandom.java StdOut.java
 *
 *  % java DoublingTest 
 *      512 6.48
 *     1024 8.30
 *     2048 7.75
 *     4096 8.00
 *     8192 8.05
 *   ... 
 *
 *************************************************************************/

public class DoublingTest {

    public static double timeTrial(int N) {
        int MAX = 1000000;
        int[] a = new int[N];
        for (int i = 0; i < N; i++) {
            a[i] = StdRandom.uniform(-MAX, MAX);
        }
        Stopwatch s = new Stopwatch();
        int cnt = ThreeSum.count(a);
        return s.elapsedTime();
    }


    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);
        } 
    } 
}